Board Thread:Naruto Discussions/@comment-25122992-20161230113055/@comment-3279282-20161230150045

No summoning animal lives in a special "plane", at least not outside of the normal world. And there is no need to do that. Sasuke's hawk doesn't live in any special place, either. Madara/Obito summoned it because they controlled it with their Sharingan.

Where was the time limit mentioned?

That's a good question, I somehow doubt Kishimoto thought about that.