2.6 Git obviously supports multiple checkouts from of the repository it is git worktree. So, after cloning it is possible to just add more directories which follows different branches, as many as you like.

Also Git repository can be cloned as "bare" or in checkout work directory. So, it is possible to have cloned repository without checkout and add checkouts in different directories...

2.5.3 commands git clone, git fetch are fetching all branches by default, so I do not understand what why such statement are provided. Au contraire git have very lightweight branches system just to allow work on multiple branches and blazing fast switching between them. So, statement that git focuses on one branch only is misleading readers.

Could you fix those mistakes in documentation? Probably there are more ... but I did not have time to read full document right now - maybe I will go back later...