Heh, so I installed a new faucet in our kitchen sink and thought I’d done a good job, I had hoses snaking all over the place and my wife was like “I can’t even use the pull-out sprayer because it won’t go back in once I pull it out.” So a few months later I call my plumber and ask if he can replace the valves under my kitchen sink because they’re old and the tolerances are outside my skill level for trying to saw them off and replace them. He comes out, spends an hour replacing the valves and then he’s like “oh yeah, I fixed all the hoses under the sink for no charge, the last guy did a horrible job, you can’t even use the sprayer!” I look under the sink and it’s like NASA came in and rerouted everything, tons of room, no crazy hoses hanging down, and the sprayer works!

I had plumbers out recently to replace a water heater.. after they left I went down to find out they had pushed the new one right up against the outlet the sump pump was using so I couldn't unplug that without moving the whole water heater. I'm not usually the one to complain that people don't take pride in their work but... it was a pretty visible and egregious error in a spacious and well conditioned utility room! Still haven't found anyone that goes above and beyond even for simple tasks.

Never mind 20 years old, I use a puller for much younger cartridges. Saves me needing the pull and pray method.

This is one of those things I believe to be more about feel.

That plumber has done this 1000 times and will make it look easy.

They can pass you tools, walk you through it, give you as much help as you can possibly receive, but you'll struggle a ton anyway. Or, as you say, break it.

Practice makes perfect. Sometimes it is still cheaper to get somebody who knows what they're doing. We can't yet remote that in.