It really depends on the dog. If you think you can trust your dog outside the crate then leave them out, if not, keep them in. Also depends on what you leave out and about. If you don't want to risk your dog eating something important, keep it locked up, if there isn't anything that major that they can chew up (or tend to chew) then take the chance.
Some dogs can be trusted at 6 months, others can never be trusted. Really depends on your situation.