I think I learned the ins and outs of coding a lot better by doing it by hand. Perhaps it helps reinforce and understand what you're doing. But, I see it being the same as being forced to do your math exams without a calculator in school: almost no one works that way, but if you can work that way, then when you use the calculator you become much more effective. It's more of a learning or training exercise so that when you are doing other things, you have a foundation to build on.