Our chickens get 9-15 hours of "outdoor time" everyday, depending upon the light cycle of the year. Our runs are fairly predator-proof, so we don't lock them into the coop at night and they can enter the runs as soon as it is light enough. Winter time most of that time is in the attached covered runs due to the snow. I could never imagine not having a run. They need more than just a few hours of outdoor time everyday, whether in a run or free-range. And yes, they will likely destroy your gardens if you don't take sufficient measures to protect everything you want to keep (think chicken wire over or around everything). You'd be surprised how quickly a chicken can tear up prized flowers, shrubs or veggies, especially veggies.
If you can have a covered (or partially covered) run, all the better, as they will be happier and dry during wet weather.