Yes, because when I first got Dudley, I was working full-time in an office. Even now, he'll go in this crate if he wants a treat, or to take a nap...I leave the doors open. Sometimes when I have to go out, I find him in his crate when I come home.
Yes, al of ours are crate trained. They will go in there on their own if they want some piece and quite, plus when we are gone they sty in there to keep them out of mischief.
Bella will go in hers when needed and I leave the door open on hers and sometimes she'll walk in it and nap in it. I gave in though and at night she sleeps with me