It's actually delicious to let Jajangmyeon soak for an hour on purpose

I tried this after seeing the video because it looked interesting, and it's actually really good lol. As long as you can tolerate a slight loss in chewiness and a bit of dryness, the flavor itself improves quite a bit.
Compared to a restaurant that does it properly, it's about the same difference as pouring sauce over Tangsuyuk versus stir-frying it in the sauce. Both the noodle flavor and the Jajang flavor are enhanced. I think I'll eat it this way every once in a while.