One advantage of bigger debris
One advantage of bigger debris is it's a lot easier to observe and thus predict (plus there tends to be a lot less of it). Given the laws of physics haven't changed lately, those estimates should be pretty good.
The one detail that might complicate estimates is that larger debris in LEO has more atmospheric drag and this means it's orbit will change (decay) a lot quicker than something smaller. I suspect that's probably only significant over a timescale of months rather than hours though.
Biting the hand that feeds IT
