I can't tell you what to do. I take the risk of disease seriously enough that the only way I add new blood to my flock is to get hatching eggs and hatch them myself. No living chickens come close to my flock. But lots of people go to chicken swaps and bring home new chickens and never have a...
Chicken diseases can be spread in different ways, through the air, through drinking or eating from the same source, eating each others poop. The more you can separate them during quarantine, the more effective quarantine will be. You can take it to any extreme you want to, changing shoes...