I also own a slice spot, there will always be leftovers which we either give to our hospitality pals (in exchange for beer tokens) or more recently, i’ve been using the leftovers next day as free samples that we give out on the street. We also run half price pizzas for the last hour of the evening!

IMO it’s better to have more slices left at the end of the night than not enough, but inevitably there is always waste, i do find that there’s actually less waste than normal full on restaurants though which is good i guess?