Is there a better strategy to quickly level up in Killing Floor 2?

I was looking for strategies to quickly level up in Killing Floor 2 and I ended up on this old question about KF1.

In KF2 we now have also "Endless mode", that is basically a chain of progressively harder short matches (4 waves + boss).

This would make me believe that if one can consistently get to a certain wave, then they would get more XPs than playing an equivalent amount of waves with short survival matches. Unfortunately this is complicated by the presence of random modifiers in the waves of Endless mode: e.g., even at wave 30+, if the "only cysts" modifier appears, the player will gain far fewer XPs than otherwise.

So, my question, is there data on whether it makes more sense to try Endless mode to get XPs faster? Or is chaining short survival matches still the superior strategy no matter what?

I realize that there could be a cut-off somewhere (i.e. "Endless is worth it only above X waves"), so I would be satisfied if there is even an estimate of how big "X" is.