Several years back there was a thread on here about someone that put a "tractor" over their raised beds in the fall/winter to prepare them for planting. The chickens would clean up the vegetation and fertilize the soil. By the time planting season came around the poop had broken down so it was safe to plant. They did not move it every day since they wanted the vegetation to be cleaned up and poop to be deposited. I think how often you would need to move it would depend on how many chickens and how big the tractor was. Whether it was over the raised bed or on the ground I'd suggest how often you move it would need to be based on your observations and not blindly just guess at a schedule.
How you would build that tractor would depend on how your raised beds were built and what size they were. As best I can remember all those raised beds were 4' x 8' and built in a way that they could sit a tractor on top of the raised beds and be held in place by cleats and screws so wind and predators could not knock them off.
My question is can I pull a few chickens from the flock seasonally to put in the tractor? How do other people use small chicken tractors when you have a medium sized flock?
I think your concern is about removing chickens for a time period and reintegrating them with your main flock. Some people do that all of the time. One example, during breeding season people remove their chickens into breeding pens isolated from the flock and put them back in with the flock when breeding season is over. If you only have hens this is easier than if two or more roosters are involved. You may be able to just turn the hens in your tractor back in with your flock when you are ready but I could see putting that tractor in the run for a week of "see but don't touch" for a week.
I use electric netting and like it. It has stopped all ground based predators. It does not stop flying predators but luckily those are not a problem for me. Flying predators are a serious problem for some people. Why were you considering putting a tractor over you raised beds? Electric netting around the area will not concentrate their foraging or poop in those gardens. It is highly unlikely the chickens will let you grow anything in those raised beds if they have access.
Do you grow a winter garden? Where you are (thanks or providing that) you can probably grow beets, carrots, turnips, radishes, collard greens, kale, chard, and other cool weather crops if you are willing to cover them during a frost or freeze. Maybe brussels sprouts, cauliflower, or broccoli. If the chickens are roaming among them you won't be able to.
I don't know enough about your set-up or goals to recommend one way over another but either can work if it is set up right.