I think realistically, about 20-30. Most of which are copy/pasted forms of triggers or parallel events that keep up with environmental coordinates, etc.
I'm extremely impressed if some of y'alls comments are true...I mean having more than a few hundred events on a single map is a LOT of work on its own...hope that 1 map is filled with content!
I feel like if I added the total. number of events in my entire game, then yeah, I'd say around maybe 600-1,000 events total or so. Though I'm one of those people that likes to break down my game into smaller maps, bit. by bit. I only really have 1 "giant" map.