So, you actually did give me a great idea, Ulco. So thanks a lot for turning gears. It seems to me duration is what's really "carving" away the valleys, as it normally would in real world. So what if far less time passed, say 0.05, but the downcutting and such was super exaggerated? You'd get less valley, but more pronounced flows!
Check out the difference between default classic erosion settings, and my idea in application with less duration and exaggerated settings.\
PS if you think about it this approach makes sense for our area here in PNW. The mountains were carved out pretty recently during the ice age, and experience heavy rainfall and storms for exaggerated erosion, but less valleying in the actual alpine zone.