"Never quit something with great long-term potential just because you can't deal with the stress of the moment."
—Seth Godin from "The Dip"
Spot on as always from Seth Godin! You should never make a decision to quit something in the heat of battle.
Don't decide to cut something from your recital program while you are in the middle of a frustrating practice session.
Don't decide that your band needs to play an easier march for assessment while you are in the middle of a bad rehearsal.
Don't decide to change career paths while you are in the middle of a terrible gig.
Any of the above conclusions may very well be the best thing moving forward. But there is never a drawback to being sure you are not succumbing to the stress of the moment.
The only way to accurately assess the long-term potential of something is to do so without any emotions involved. So avoid doing so in the stress of the moment.