Three cats, three litter trays, all in the top floor bathroom. I clean them in the morning, DD2 does them at night, and we both remove poos as soon as we see them.
They're supposed to have a tray each, but ScaryAg has decided that both covered ones belong to her, one for wees, one for poos, and the poor boys have to share the third 
They're all indoor cats, and with the exception of Max, always have been. Ag is too arrogant, and would expect cars to stop for her, plus she's a Bengal and if be terrified of someone stealing her, FailCat is simply waaay too stupid to be allowed out. He got out by accident the other day, and was recovered cowering in a flower bed half an hour later, screaming for help. He's a danger to himself tbh. Max is a foster cat, it would be irresponsible of me to allow him out, as he's not mine. They have the run of a four storey house, lots to do, and each other to play with. They are all sleek, healthy, and show no signs of stress or unhappiness. I would never let cats out, far too much chance of them being knocked over, stolen, or simply disappearing, not to mention the impact they have on bird life. The last reason alone is enough imo to always have house cats.