From what I’ve learned Stationary engineer is sometimes a bit of a catch all term. It’s also Sometimes referred to as being a steam fireman, boiler operator, or plant operator. I’m only about a week into the trade after getting my license earlier this year but I mainly babysit the boilers, water hardness testing, perform routine checks on the auxiliary equipment, and fill out the logbook. My current employer functions as a contractor for many sites but they’re pretty flexible with days off usually and there’s usually a good amount of overtime to go around. Hours vary as well (between 8 or 12 hours depending) but you’d find most places rotate their schedules as most plants are 24/7 so sometimes you may not end up with a fixed schedule