I try to compose a formal model and algebra of the codebase - quite informally, mind you. Takes a bit of pen and paper and a few caffeinated drinks usually.

People really do learn quite differently and everyone needs to find their mode of learning - there is no one single true way. This is one of the most important skills in software development, IMO. Once you learn how you learn you can apply it to most new contexts.

I write stuff down because for me that-the process of writing seems to be the most effective way to learn.