Does that depend on the machine? I can't imagine someone with a big pro machine standing there unrolling the vinyl by hand while it cuts 30 16' banners.
yes it depends on the machine, big expensive ones come with power feed & take up spools for large unattended runs.
I dont know of anyone who would cut 30 16' banners unattended, one mistake could be very costly.
I dont believe they will be cutting that long of a run with a 15" desktop plotter.
smaller machines are not made for those situations and require a bit of babysitting, most that dont come with a stand or feed roller are not made to feed off a roll anyway. it also depends on your cut speed, I run mine @ 700 ipm so if it tries to pull vinyl off the roll by its self it will cause the material to slip and ruin the cut