I use hopper timers, I have had up to three or four, but currently only one.  They are used for harvesting growing things of all shapes and sizes 😀

I’ve also used them as pulse extenders and other things as well; however, haven’t had the need on this server yet.  I can’t imagine minecraft without these really… I mean, I’d have to like remember to go push a button or something 🙁

Why not just ask everyone to limit their own usage of these and see where that goes, but I’d say if these are tasking the server then they are probably doing useful things 😀