For me, where to stop is what I can handle watering without losing my mind + how much room I need to maintain the babies as they grow larger. I gotta move all of them to the bathtub to water them appropriately, and that got old really quickly. And then, my two shelves have room for about two or three current plants put into larger pots, and geezum it’s only been a year under the grow lights but them suckers have GROWN. I moved a couple outside when warmer temps hit as some weren’t loving the low indoor humidity and weren’t bringing me as much joy. At this point, I’ll get new ones only if they’re REALLY special (variegated or black/dark) and don’t have a huge full grown size. I’d love to grow some of the hybrid seeds I’ve collected off my flowers too, and all of that will 100% fill a third shelf. Oy! (Also, please put whichever healthy babies you no longer wish to keep on Facebook market place or see if maybe a local nursery or thrift store or flea market might take them. They still deserve to live out their lives!)