how often do you move the tractor/ coop to give them fresh forage area?
When I need to. I haven't used a tractor in years but the conditions would tell me when I needed to. With mine it was usually every two or three days. Rain had a lot to say about that.
I had eight mature dual purpose chickens in a 64 square foot tractor in Northwest Arkansas in early summer. The area I was using was pasture, not a backyard lawn, so a different turf. It was well-established turf, mostly Bermuda grass. The soil was a silty clay, if it got wet and was disturbed it became a really sticky liquid mess. We all have our own conditions so our results may be different.
If I left it too long in one spot the poop would build up and start to stink, usually three to four days in relatively dry weather. In wet weather it could be as little as two days. If it rained and the ground was wet they'd churn it into a fine mud sometimes referred to as baby poop. It had a lot of similarities. If the ground was wet and it was rainy I might move it every day. I don't recall ever going for more than four days even when it was really dry. The poop under their roosts would build up an start to stink.
When I'd move it the grass was pretty much gone, just a bare muddy spot or very dirty grass. Within a week it was covered with green. They were not on it long enough to scratch out the roots. When it grew back the growth was dark green and lush, the poop really enriched the soil for a short while so I'd have spots of dark green wherever the tractor had been.
What your tractor looks like has an effect. Mine was fully enclosed so they were limited to what was inside. Some people use a tractor more as a spot to sleep and keep feed dry but surround it with electric netting to keep land-based predators out of a large forage area. They don't have to move those that often, either going by when the forage is used up or the poop under where they sleep getting bad enough to stink.
Some of the things I think determines how often you have to move a tractor are chicken density, soil and turf types, weather, time of year (your local climate), the actual chickens you have, and how picky you are about what the area looks like after you move it. Some people raising Cornish Cross for meat may move their tractors twice a day. Others can go several days or over a week, especially if they have just a few chickens in a larger tractor, bantams or young chicks can make a difference too.
I think each of us has to determine our own schedule based on what we see. Using a tractor is a commitment to being able to move it when you need to. They can make it hard to take a trip, whether that is a planned vacation or wedding or a surprise funeral. Depending on your climate you might want a tractor in the good weather months but a fixed coop/run for winter. I found it beneficial to have a fixed coop/run when I took a trip or was sick and did not want to move the tractor every few days. Many people really like their tractors but they can come with logistics issues.
Good luck!