One of ours never goes out, the outdoor world is far too scary (she is, to be honest, rather strange, varies between being totally besotted with us, to being utterly convinced that we are cat murderers. She will sit on the end of the bed, purring and doing that "smile" thing that cats do, then I pick up my roll-on deodorant and she runs as if the hounds of hell are after her. Although she is adopted, I find it hard to believe that she was traumatised by a bottle of Mitchum in early life.)
Eldest cat, also adopted at quite an age, had never been outside until we had her. Is now a total sun worshipper. Good weather, outside, warming her old bones until she is so hot that she is hot to the touch. Anything less, indoors, preferably in the airing cupboard if she can nip in before the door is shut. Will only "go" in the litter tray, obviously thinks that is the right place.
Maurice, we have had from a kitten, goes in and out at will. Well, sort of. With Mr Phoenix being currently at home all day, Maurice regards him as a sort of concierge. The amount of times that he goes out, in, out, in, out, in..............