I'm genuinely curious - would you be so kind to share what kind of coding do you do, and for how long have you been doing it, when you can code for 12 hours not needing to look up how to do something online (syntax, example for a best way to approach something etc)? I'm asking because this is one of my worst fears - how genuine of a senior, experienced developer am I, if I probably wouldn't be able to do 2 good hours of progress without the internet...
I've been forced to work without the internet for large swaths of time. In the beginning its a pain, but once you get all the resources you need local, you can speed up past what you can do with the internet.
The key, for me, is to work without the internet, keeping a list of things you need and when you hit a hard snag, go online, grab all the things you need, repeat. This allows you to slowly accumuate almost everything you need local.
Now you have the ability to full-text index the entire shebang and when you get to the point of real-time responsive full-text search on all your manuals and all the source code (libraries included), you'll be kicking yourself for not getting to that point much sooner.
It was truly a game-changer for me. Googling for answers and filtering through the crap is a huge time sink.
It depends on what it is. If I'm doing something in C, it's much less likely that I use the internet for anything. C and Unix grew up before the internet. Man pages are installed on local system for quick and easy reference.
If I'm doing something in a less familiar language, library, or framework (or even new techniques), then I fully expect that I'll rely heavily on internet to find code samples, reference, and documentation.
I do a lot more writing than coding. But, while I used to be able to do stuff surrounded by books, absent an Internet connection, I'd have to work through something with lots of [need to check], [flesh this out when can look up], etc. if I tried to do anything in the absence of an Internet connection.
Went on a berserk coding spree from 1PM to 1AM with some small breaks in between. Completely cut off from any distraction, I was able to concentrate.
Willpower and discipline are nice, but real restrictions that are impossible to circumvent are better, at least for me.