I can't speak for the mechanical controller, but maybe can shead some light on the electronic controller, since my cs020 has one.
I was convinced that my smoker held tight temps since I could see the temp readout on my display and since I bought it in the winter I only checked ever hour(really cold here). I took the smoker to my trailer at the lake,set it on the back porch and here is where things got interesting.
I just sat around in the afternoon with a few cold drinks and an extra probe dangling in the top hole. I don't believe anymore that the temps are as tight as I first thought. Early in the smoke when coming to temp the display read 235*, but the top one read 280*. Later in the smoke the display read 235* and I'll be dang that's what the top read.
I did a turkey and late in the smoke with the temp set at 300*, the smoker display read 258* and the top read 298*. Oh well, trust me it turns out the BEST Que that I have ever ate and I live right in the middle of Que country.
I haven't had any problems smoking my Crappie and it is a short smoke period.
That smoker you have has a long history of excellence, I believe, almost a half century.
Don't worry, you're going through the Newbie pains of smoking on an electric smoker, that seems like it can't be a simple as it is. Trust me, I tried to over think my first couple months and I'm dang glad it was cold out so I couldn't stand over it and worry about the temps.