I read a case study from a plant in Ohio where the mud drum had close to 5 inches of buildup after only 3 years of no treatment. They ended up cutting a section out because the scale had bonded so tight you could not chip it. Four years sounds about right for that level of neglect, maybe even on the shorter end depending on their water hardness. Once it gets that thick it acts like insulation, so you are burning fuel for nothing and risking tube failure on top of it.

Eleven auto renewals is wild but the one that got me is the fitness thing from when you swore you'd get into yoga. I did the exact same thing with a $39 a month pilates app two years ago and I kept telling myself I'd cancel after the free trial ended. The free trial ended in March of last year and I finally killed it in October. That's like $230 for an app I opened maybe four times. The worst part is they send you the little "we miss you" emails and I would open those and still not cancel. It's like the subscription becomes part of the background noise of your life and you stop seeing it as real money. Good on you for finally sorting through the whole 60 days, I still haven't done that and I'm scared what I'd find.