Yep , attended one of those about three years after resigning as an elder - along with two other "deleted" elders an aging MS and about six others that either can't hold down a job, can't get out of bed, or are depressed. Or clever.
Basically it was you need to be averaging 8 to 10 hours minimum, be early for all the meetings and be "visible" in ministry.
This is why my report was always put in at 5 to 7 hours - just enough to be allowed (gasp) to run a microphone - better than sitting still through an hour and a half of drone and moan - but not enough to read the watchtower.
Really they had a hierarchy.
Anyone could clean the hall (of course) even on restrictions.
Irregular up to 4 hours nothing/zippo/nada - oh you could bring some oldie in your car to the hall especially if they stank of urine.
5/6 hours - run a microphone, be an assistant to an assistant on the hall dept
7 hours - read at the cong book err bible study - be an assistant on a department or (if you had enough fingers that worked) operate the sound equipment desk
8 hours - read the watchtower! Yay! Stand in as an exemplary brother for an MS department because they never had enough. Often an ex elder who toed the line.
9/10 hours - be considered for MS if you could get to all the meetings early and if you were visibly supporting your group in first call while the elder left after fifteen minutes to do calls.
I don't know about now but they are pretty desperate - I'm sure some of the guys used are hardly regular.