Well, to me, git's DAG model is 100% obvious, and gitk --all is helpful in exactly the way you state — but at the beginning it was still confusing which command used how would produce the effect on the DAG (and working tree and index...) I wanted. Similarly, the commands to configure and manipulate branches and remotes are not entirely obvious, especially if you've gotten off the beaten path and want to fix your config to be normal.