What typically happens is a "mechanic" will pull the little rubber plug on the backside of the backing plate and proceed to "adjust" the brakes with a screw driver.. Extremely easy to either back off the adjustment or way over tighten the adjustment from that little tiny opening..
The mechanic has zero idea as to which way they turned it, how much it turned and how tight they made the adjustment and no way to know if it was done correctly without at least lifting the tire off the ground and giving it a spin..
I never use that window, I always pull the drum. This way I can inspect the condition of the shoes and mechanical parts and if needed adjust the shoes.
Depending on the miles you tow, may only need to inspect and adjust once a yr or once every several yrs. Doesn't take all that much time once you work out a plan of attack. For me, 10 minutes per wheel, that's about 40 minutes of my life devoted to my safety once a yr..