I often go in there. Make sure all lights are off. Usually sit or lay in bathtub with just shower on. Close eyes and relax and think(and daydream). It's sorta like a combination massage / isolation chamber effect for me. Spending time doing this daily keeps me centered, focused, clear minded, and lastly reduces any temporary stress I have.
A chunk has no context. Context is how a chunk fits into the big picture of what you already know. At a neural level, context means neurons are making new connections. Think of a chunk as the WHAT. The context as HOW you use the chunk you are learning.
For a learned chunk to be useful, you need to know HOW a chunk is useful. You need to know the CONTEXT. Context is knowing the HOW and WHEN to use what you have learned. If you change from focused learning to relaxation, you can let your un-focused mind create these connections. 
By letting the brain drift into diffuse mode (unfocused attention), you are making connections between chunks, creating context. The brain is doing this at a lower level of conscience by sleeping or relaxing or changing focus. You use a bath, Darwin had his ^thinking path^ for the same reasons. ,
 "Learning How to Learn: Powerful mental tools to help you master tough subjects" ~ https://www.coursera.org/learn/learning-how-to-learn
I thought this was mainly computers that taught me to think this way, didn't realise there was documented philosophy behind it.
Chunking is described in more detail at Week2 https://www.coursera.org/learn/learning-how-to-learn/home/we... and books:
Continuous water heaters are a must though :)
Although if you live in the midwest like I do, we have infinite water. Use more water? it goes back to lake Michigan and recycled. The gas to heat the water is the only "waste", but you could offset with a solar panel.
Why wouldn't the energy required be at least linearly correlated with the water amount?
Is that reasoning unrealistic? I don't know a first thing about water treatment.
To take a local example I am familiar with — Seattle gets most of its drinking water from the Cedar River watershed (rainwater). It is a relatively pristine source. Wastewater, including shower output, is treated and released into Puget Sound (the ocean). The only way that ocean water makes it back into the drinking supply is via ordinary evaporation and rain.
So the treatment required on the second quantity of water is exactly the same as on the first, and you get linearly increasing cost.
I have also begun to note a new state that I let go missing, and that is being thoughtless. It is really hard for me to achieve but I can in situations like focusing on music or on the opposite spectrum, motorsport. I always think so much more clearly afterward.
I thought about filling the tub with hot water and purchasing a high powered pump to circulate water to produce a shower effect.
There is a link in the article to some words from John Cleese where he talk about creativity being a "mood" - and I find this to be true.  The hardest part, I think, is probably finding the activities that really do it for you. And that is really just practicing a bit of mindfulness while doing things.
For me, showers and baths bring a different sort of creativity than walking a well-walked path, doing a repetitive task (even if it is part of another creative endeavor), or simply listening to music. Combining music to the other things seems to help as well.
There are a lot of things attributed to dopamine these days, and it feels like it can't possibly be that simple. If it were, dopamine injections would be a great thing. It's kinda like brainwaves. Maybe it serves as a pretty good indicator (dopamine for 'pleasure', brainwaves for how relaxed you are) but it is simply small-minded to assume that dopamine alone is responsible for everything. Just like brainwaves aren't the end-all of psychology.
Also, I feel weird telling anyone it came to me while I was in the shower. Like I'm putting the image of me in the shower in their head.
I really like the fluffy hair feeling i get when i wash most/all the grease out.
But sometimes i can wash my hair 4-5 times and it's still greasy!
I'm more likely to mindlessly apply body soap to my hair or shampoo to my body when solving problems in the shower. I'm always amused when my autopilot makes this mistake.
Solving these problems is really hard and energy consuming process.
So every week, for more than a year, I'm experiencing getting stuck and being really frustrated, having insights on morning shower etc.
I read this article and I don't find it practically useful except may be it's a nice reading about dopamine or other stuff like that.
I've noticed that to have an insight in morning shower you have to think really hard (and probably being frustrated of getting stuck) a day before. You have to be involved in the problem. Only then, your brain start thinking about it in the background. If you are not involved in the problem, you won't have insight in morning shower. I even suspect that being frustrated day before could be one of key factors why your brain prioritize task of solving a problem in the background.
Unfortunately, I don't see that this article mention that.
I think in general your brain could have two modes of solving problem - deterministic thinking, random-walk thinking.
When you are actively solving problem, your brain works in deterministic mode.
When you have insight on morning shower, your brain works in random-walk mode.
So probably, to get unstuck, you have to switch from deterministic mode to random-walk mode. In random-walk mode, you can randomly jump from one branch (dead-end branch) in decision tree to another branch which could be correct one.
Solving olympiad problems is NP-complete (or NP-hard, I don't know). It means that there is no way to solve them deterministically in reasonable amount of time. Probably, our brains evolved in such a way that it uses heuristics with random elements to tackle NP-complete problems in real life.
On the contrary, the systematic method to hack these seems to be pattern matching and shoehorning into similar problems rather than reasoning from first principles. I'm going through a similar battle, mainly because programming interviews have annoyingly become competitive challenges lately and before adopting a strategy it was an extremely soulsucking process.
Let's say there is a relatively simple olympiad puzzle. Also, let's say there is a imaginary robot which should solve this olympiad puzzle. What I said there is no fast universal algorithm for the robot which allows to solve any such olympiad puzzle. The only thing robot can do to solve many (but not all) problems is heuristics with random elements.
The Robot has to check n p-complex approaches to m problems.
This has complexity n.m.p'max I think that's in p.
All the problems that are known to be p are in n and m.
Before, I used to go for a walk to do that. I also had ideas under the shower. I have found meditation to be more efficient in term of focus.
Forcing myself to do these things has been one of the biggest improvements in my life, in particular in dealing with my anxiety and stress issues.
And nearly every programmer I told about this had experienced the same thing. ;-)
It’s part of what déjà vu is. Your brain already pre-calculated a thing that might happen a long time ago when you weren’t noticing, then it actually happened and you're like - Hey wait a sec, I kind of recognize this shit. Shower thoughts are broader, because the range that we use for our creativity is actually limited by our surroundings. For instance, if we're in a social setting around a lot of people, our brains would try to optimize the relations between people, the environment, the posture. There are so many social things that go on in a social setting that occupy your mind, like trying to understand what other people are saying, trying to educate them, tell them things etc.
It’s very consuming to the mind, so when you are in the shower you probably don’t have music, you probably don’t have to think where to go next, or people you are trying to impress. It allows you to free your mind to create and synthesize new ideas using a broad range of inputs that can be a lot more random. This is because they’re not being refined or restricted to the same content matter that exists during the rest of the day, whether we are being influenced by work, or school or by a lover or any other type of social setting.
This what I do when it is socially unacceptable to hop in the shower for the third time in the day.
maybe relevant to your theory: http://content.time.com/time/covers/20060116/pdf/Day_Night.p...