New developers spend more time learning the Version Control's structure before they can start coding.

Your history becomes harder to understand, which makes it less useful when you really need it. You can get some useful output with submodules or subtrees, or through other scriptable methods, but it's just not the same as typing tig -grep= or git log -grep= and scanning all the commits you care about. History traversing commands like git log just don't output history as meaningfully with fractured repository structures. Tracking the entire history of a feature is much more difficult.It's possible, it's just not as easy, meaning bug-hunting in times of crisis is that much harder. Tools like git bisect become much more difficult to use when you fracture your repository into sub-repositories. It's harder to discover when bugs were introduced.These are less true if they are truly distinct projects, but from the sounds of it changes to one often require changes to another, which can really exacerbate these problems: There are three major disadvantages to 'one project per repository', the way you've described it above.

Setting up github android studio 2012