Well here's how I see it...
If you can do XXXlbs/kgs on an exercise you can probably do XXX-100 for 20 reps. Those are just round examples, but the point is that you're obviously going to need to be able to be pressing something a lot higher than 100kg. This should be obvious though.
I feel the benefit of doing higher rep training (20 range) is to acclimate you to enduring it. I imagine the training effect would be along the lines of making your muscles more efficient at producing the work with less fuel reserves. I know my horizontal pressing movements fatigue VERY quickly, and very SUDDENLY. I'll be banging out reps 5 and 6 as if I were on reps 1 and 2, but then number 7 is next to impossible. Anyway, so if you can handle 20-rep sets better, you may be able to hit 100kgs without having to increase your absolute strength as much, you know?
Just some thoughts.
(By the way Kevin Levrone mentioned in a recent video something about a 'rule of thumb' in which he says, "The rule of thumb is if you can do 225 lbs x 10, you can bench 315 lbs". FYI 315=142kg and 100kg=220lb)