Well - it used to be that way. I was always told to tip based on performance, but have gotten a lot of scoldings over the years for doing just that. Hell it used to be 10% was the average tip, now it’s 15 and 20%. I’ve even had waitresses come up to me as I went out the door to tell me what I left wasn’t enough and been told by members of my party that they would chip in if I was short cash after already putting down 15%.
That being said when I’ve had absolutely stunning service I’ve left a $40 tip on a $20 meal, etc.
I like this myself. Reminds me of Japan where tipping is an insult....it’s interpreted there as the person obviously isn’t good at what they do so likely need some extra help.
If the service stays good, I would be more than satisfied (as long as the value remains good for the customer).