You'll learn which moves you actually can pull off against a resisting enemy if your training includes free sparring instead of just practicing those 'fancy moves' against someone who mostly cooperates. About 1/4 of our Jujutsu sessions is ground randori, and of the dozens more or less fancy moves we learned I used rather few in there(granted, a good number assume you are standing instead of on the ground). I usually just go for the throat, and I'm at a point where I can reliably choke someone with a bit less experience with no way for them to get out of the hold. Quite useful I think, as I surmise street thugs are more likely to train a martial art focused on kicking/punching than wrestling.
I'm still rather novice, so I still need to get to the point where I can use most moves against someone who really doesn't want me to. Most things I do are improvised and less than ideal. Though I wish I could replicate that joint lock where I used just my legs.