I had two or three and bought two on an impulse. I only utilize that many once a year but I like it. I brew three or four that take a while before they're ready to drink and one or two that are relatively fast (one month). It helps for not staring at fermenters a couple of times per day.After several decades of brewing, I just invested in 2 extra fermeters. Now have a grand total of 4. So now, at a cost of 15 extra quid, maybe I can have a bit more patience.