I believe in crate training myself. All 3 of my dogs are crate trained, and go to their crates on their own, and when I'm ready to go to work, they are in the crates waiting for me to close the doors. The longest they are in is about 4.5 hours, then I'm home for lunch and play with them and have them go potty for 40-45 minutes, then it's back in the crates for another 3-4 hours. Then at night, they sometimes sleep in their crates on their own terms, with the doors open. Or they sleep on the bed with me. Their option.
Another thing to add about crate training, you really need to make the crate a FUN place. You don't just put the dog in until they get used to it, or not like it at all. I played lots of games with my dogs and their crates and it's not only a safe haven for them, it's a place of fun as well, and a place to relax.