I was level 36 at about 90% experience.

I enter Foul Cascade where the monsters are level 30.

I emerge victorious at level 37 and about 5% experience.

I noticed the regular monsters were giving me a pitiful 52 experience each.

So I think that it would be a good idea if the experience you gained from normal dungeons was normalised so when you're at the high end of the level cap, you aren't getting practically nothing from it!