I don't think it is even "necessary" to finish a quilt - or quilt top - sometimes it's like going to a buffet - it looked appealing, but wasn't so great after trying it!
Some people are Energizer Bunnies - some people are more like tortoises - but eventually get to where they want to go.
I am sort of a slow one, myself. So, of course, I think it's okay to be slow. (And there are some activities where "slow" makes them more enjoyable!
l - like savoring an ice cream sundae!)