We crate both our pitbull and our shepherd when we are at work and sometimes that can be near 10 hours. Neither dog seems to have any problems and most time I arrive home and find them sleeping. We just make sure that they both get out and excercised eachday. And like you its about 3 days a week. We try to break it up since we both work shift work and are on opposite times ( I wake up when he arrives home and when I return he has just left to go back). So most those times in the crate are really when we are sleeping.
Each dog has two crates, one is called “kennel” and those are kept in the livingroom and that is where they are when we work or are out doin errands etc.. At night we say “bedroom” and they run to their crates located next to the bed. I think its cool for people who like to sleep with their dogs but it never hurts to have them used to being crated at night just incase there is an unexpected reason for them to not be in bed with you. I know my cat appreciates them not in the bed since they would spend more time tormenting her then sleeping. = )