The first two-thirds of this tutorial seems to be focused on breaking down the components of a standard subtractive synthesizer (essentially the synthesis process itself). However, it doesn’t really delve into how these components are interconnected or how they operate as a cohesive system. The latter part of the tutorial is more aligned with what you're referring to.
That said, the knowledge gained here isn’t universally applicable to all synthesizers, it's only applicable to Subtractive Synths. If the tutorial took just one additional step, it could provide a more complete foundation, but as it stands, it leaves you wanting more (or worse, not know you need to know more).
For a more versatile pointed approach, I suggested using something like VCV Rack, because Its modular interface allows you to import only the modules you need to explore or explain a specific synthesis method. This hands-on method enables you to experiment and internalize the concepts, which can then be applied to the synthesizers you have on hand.
Most tutorial videos are 5-10 minutes long, and completely reproducible and it's very clear the signal flow from one part to the next.
Fair enough. I should try it, although I have a pretty good grasp of how subtractive synths work. What about FM synthesis, do you have any suggestions on that? I find it the least intuitive by far, not that my experience extends to many other kinds (I mainly use wavetable, sample-based and subtractive synths these days).
I'd still do the first tutorial above, so you can understand how to use VCV Rack, but here is a small tutorial (10 minutes.) That will help you understand what's going on under the hood of your favorite FM synths. He doesn't do this in the video, but I would attach the output to the oscilloscope module to get an intuition for why certain parameters affect the specific harmonics that give FM its characteristic sound.
Your FM synth at home is 100x more time complicated than this patch you build but if you grok what's going on here, you should have a better idea of what going on in your other FM synths.
Most tutorial videos are 5-10 minutes long, and completely reproducible and it's very clear the signal flow from one part to the next.