I have two cats.
One likes to be outside as much as possible (from when we open the cat flap at 7am - sometimes later at weekends - until we lock her in in the evening). She stopped using the litter tray ages ago, and goes outside.
The other is much more if a 'home cat' and although she does venture out it's for much shorter periods and she comes home frequently. She has always used a litter tray until recently - she hasn't used it for well over a week.
I'd love to get rid of the litter tray. Shall I just remove it and see what happens? I'm worried about when winter comes and we lock them in earlier in the evenings. Can they really hold it in all night? The second cat has been indoors since about 5pm last night and hasn't gone out even now I have opened the back door.