You provide a service that is consistent with the customer's level of satisfaction.
Last week, I took a job from a client who wanted a whole bunch of old Kodachrome slides scanned to computer. There were 150 of them.
In order to scan all those slides, adjust exposure, adjust color and retouch all the dust spots it would take quite a bit of time. Yes, infrared dust removal works but it doesn't catch everything and it sometimes leaves artifacts which have to be retouched or else the slide needs to be rescanned. To do them the way I wanted to do them, it would have taken weeks of working in my spare time but I wanted to deliver the project as soon as I could.
In order to do a good job and still deliver in a reasonable time, you have to cut corners in one way or another. You just can't spend an hour on each image cleaning up every speck.
So, what I did was to scan about a dozen of them and showed the results to the customer. I made a couple of them the way I would do them for myself, the "good way." I made a couple of them by cutting a couple of corners and I made a couple more by doing them the "quick way." I let the customer pick the level of work she wanted. She picked the quick way.
Even then, I still spent a little more time working on them than the customer asked for.
I always try to do things just a little bit better than I think is "good enough."