Actually, being a custodian is incredibly repetitive which is why I liked it. It was exactly the same thing every day, a perfect routine. And if there is one thing that is true for bipolar its that having a routine that doesn't change is incredible. You can say I'm queen of the rut. I hate when things change, even slightly. It takes me months to adjust to small changes in routine. I'm still not adjusted to the routine change that happened with taking my son to school, and he's six and started school when he was 4, I still struggle to get a routine going on that. I'm still struggling to get a routine since the still not adjusted routine changed again when the baby was born. Repetition and routine is essential to my functioning, which is why I loved that job.
This is why the schools were so good. You set up a routine. You do one task at a time. You have an area that is assigned to you and you do that area only. Elementary schools are the easiest and best. I would vaccume all the rooms and the hall, and empty the trash. Then, you have 1 set of bathrooms. It usually doesn' take the whole time, and then once the custodians are done they all sit in the break room and hang out.
It was so low stress. It's too bad your son wouldn't be able, that was perfect for me. And I was dumb and messed it up. I've tried to get hired back but they never even look my way now.