If something is worth doing, it's worth doing well. I think that is true for some things...surgery, accounting...whatever. But if I try to use that to run my life, I feel obsessive-compulsive.
I think "a lick and a promise" describes a lot of my attitude. A stitch in time saves nine is a good one for me.
A penny saved is a penny earned is understated because tax has to be paid on a penny earned. I guess it depends on how the penny is saved whether or not tax is required on it.