The ordered keyword is a quick and easy way to build the subprojects in the order you want.
The correct way is described in the documentation but also on this nice article.
@SGaist thanks for the article, it is very interesting and useful, anyway even by switching to the suggested configuration (avoiding ORDERED) did not solve the issue for me.
Basically you should be able to start the Android make on a command prompt outside of Qt creator at the same location where qt creator does. When it would be concurrent under these conditions it would point to some specifics of the Qt run environment for starting Android make.
I have not experienced such a behaviour so far. Therefore I consider as odd.
I completely agree with you, my only fear is that QMake is doing something wrong when creating the top-level Makefile and it's somehow preventing the build process to go parallel. I could try writing a custom Makefile just building the subfolders, I'll let you know!