[com2kid]

If I spend a couple hours reading I can understand how git works, but I'm going to forget an hour later because it is so damn complicated with all the different details that my brain flushes it's cache to make room for something with less violently confusing edge cases.

[Tor3]

For understanding git internals I went through "Git from the bottom up", a simple document with examples you type in, just to see what's going on. Many of those examples are raw git commands, nothing as sophisticated as "git commit". Easy to read, doesn't take long, but leaves behind an understanding that isn't maybe fully obvious at the time but makes everything much easier, forever. I've recommended that method to many coworkers and it seems to work well for most people. It doesn't need hours of reading either.