It really saves a ton of money, because then you can just do it yourself. Like replacing the dimmer switch with a regular switch - costs about $2 from the hardware store for the switch, and a few minutes.

Having a plumber show up costs $300 just for him to come to your house. It pays off big time to do what you can yourself.

P.S. I always ask for permission to watch them work. They appreciate the ask, and so don't think it's creepy.

I find it offputting if a mechanic doesn't want me watching him fix my car.

I want to be sure everything is done correctly!

If you want it done right do it yourself, or double check others are doing it properly!

Yes. They've never said no. I ask about their tools, their technique, etc., and they seem happy that someone is interested.

You hang out in their shop and watch them? They allow this?

I always ask. I myself hate working when someone is standing over me watching, so it only seems right to ask for permission before doing that to someone else. Basic politeness is free.