Should you really take breaks between workouts?

I've always been told your muscles need to rest a day after weight training to grow and rebuild. But then you'll hear about an actor who had to beef up for a role and they work out like 5 hours a day, 7 days a week. I'm currently on a monday - wednesday - friday workout schedule. But I'll go to 7 days if it will help. If it worked for Hugh Jackman, why can't it work for me?