I carry about 80% limpets to my Cargo space, so if i have a 200 cargo space i start out with 160-170 limpets. If my cargo space is running out and i have just found the Dream 3 'P' rock (Painite, Platinum & Paladium , rare as rocking horse poo), then i power off the running limpets in modules, then drop 4 more and power these off. This destroys the collectors and then fire off 4 more and instantly i have more cargo space for that rich rock. Limpets are Cheap 102 Cr's missing a ton of Painite is costly!
I like to be very picky when it comes to what i have in my Cargo space, unless i need some for a BB mission, i eject anything Not beginning with a P or G, and i find having 4 collectors gives me more control on what and when to Vent. As the 'Mining' bug is still in play, the hopper gets jammed, so having a bit of useless stuff to vent from the hopper is always good and gets the refinery going again!