"Contact every customer after a few days to ensure maximum satisfaction"
Hi, is your MOT ok?
Hi, does your new bulb work?

That's a bit over the top, could even lead to maximum irritation. I would only do that in exceptional circumstances. Pretty sure my customers would contact me if there was a problem. That then borders on a complaint, the customers intial attitude and how I deal with it will distinguish between "slight problem" or "complaint"

An over enthusiastic factor manager called me early one morning to ask if I needed any thing. He won't do it again.