Owning a job first
I still make most of the calls at my company. The times I handed something over early, it came back to me as a backlog, in worse shape than before I gave it away. That's when it felt like I owned a job rather than a business.
The usual fix is to write the process down, hand it off, and grow without adding my own hours. That's the happy path. Written before you've lived it, it's a wish on paper. You can only write the handbook after you've run into the places where the thing breaks, because those are the parts the next person actually needs.
There's a harder version of the same problem. I built the product around a problem I had myself, so I understand it from the inside. For someone to take it over, they have to feel it too. Explanation gets them part of the way and motivation gets them a bit further, and if they've never had the problem, that's usually where it stops.
Which puts the weight on hiring. The question at that stage is whether this person could become another version of me on this, and you need more than one of them for a business to run past its founder.More than one, because a business that runs on a single successor has moved the same problem one seat over.
The other signal I watch is surprise. If I can't remember the last time the work surprised me, I've stopped learning the job and started just doing it. That's the point to hand it over.
I'm not there yet. The frontier keeps moving and the team has to move with it, which is either a real reason or a comfortable one. I can't always tell.