I'm pretty sure that this has been discussed before, and it was revealed that each time you click save equals one edit, even if you changed multiple things at once (street name, directionality, city, road type, etc). Same goes for mass editing... if you select five sections of road and edit them in one steo, I believe that only counts as one edit (rather than editing each section individually and receiving credit for 5 total edits).
Again, this is just what I believe was said by the waze team. I could be wrong. When I'm on a computer oi rather than my phone) I'll try to find that thread).