As someone who has been writing software in one form or another since the late 1970’s all of this is true. I can’t tell you how many times I have seen the same problem again over the years, knowing how to solve the problem even if the computer, operating system, language and entire programming paradigm has changed is important. Keeping a history of what you have done, vital — I sometimes wish I still had some of those old assembly language, BASIC or FORTRAN programs I wrote back in the ‘70’s just to see if I remember them right. But they are long gone. For someone just starting out save your work, keep it around so you can reference it if you want to. Document your designs — even for your little home projects, there are so many little tools that I have on my computer when I use the one I only use occasionally, I have to bring up the code to remember how they work. Documentation or -help command line options are always good. Think about how and when you might use this again, because you will!