I understand the sentiment, but I don't get how you could draw more complex software plans by hand. I usually use Draw.io/Diagrams.net, and the drawings get pretty large and need reorganizing dozens of boxes several times while planning the architecture.
OTOH if the plan is very simple and obvious, and can be drawn out in one go, it doesn't really need a diagram in the first place, so I skip spending time drawing the obvious stuff.
I don't often do very complex software plans like that. My working notes are often on a smaller scale like individual features or so. If we need to document the full architecture for the project, I'm happy to do that with digital tools.
But while I'm planning parts of it or designing it, I do better with pen and paper. My main issue with many of the digital tools I've tried comes down to the added friction if I need to switch to a different tool in the app when I switch between circles and rectangles and text and the fact that I find free-hand drawing with mouse really difficult.
> OTOH if the plan is very simple and obvious, and can be drawn out in one go, it doesn't really need a diagram in the first place, so I skip spending time drawing the obvious stuff.
I think there's a middle ground where it might be easy to draw on one go but deciding what to draw and how things work together and what's needed requires iterations and for that, thinking through drawing and writing helps me a ton.
I guess there's many cases where you don't really know how complicated or simple the solution will end up to be, and start drawing it while thinking about it.. I must admit that those are usually the most interesting parts of the work.
I actually do all this stuff in my head and use hierarchies of bullet points in a text file to externalize some stuff. Some of these may end in arrows that point to a different process.
I never use paper because I'm always moving these bullet points around and inserting stuff between them. Apps are too slow.
I never write down all the information because these notes are enough for me to reload everything. It's pretty easy to see that I didn't write something when there's a gap in my notes. I never wrote it down because I'm going to come up with the same or better solution quickly.
This isn't really helpful for anyone else and doesn't work well with pair programming.
OTOH if the plan is very simple and obvious, and can be drawn out in one go, it doesn't really need a diagram in the first place, so I skip spending time drawing the obvious stuff.