Proper way to handle Event Manager (with multiple Canvases, etc)

Noob here…but I’m running into the multiple Event Manager warning a lot. I know how to get rid of it, but a lot of objects seem to automagically add Event Managers to them (Canvases…but also I think other things). I know I can disable/delete one or more and the issue goes away temporarily…but I’m trying to figure out what the “correct” solution is for these. Should I have one at the root level? Does it even matter where on the scene in the hierarchy it lives, or will one work everywhere within the scene regardless of it’s parent/children?