Endless disc brake issues We've purchased a new e-bike for commuting, its very heavy and carries a heavy load, and the commute is through a very hilly neighborhood. The mechanical disc brakes have become a constant issue, loosing nearly all braking power in usually about a week's time. I've cleaned the pads to remove the glazing (light sanding) and 91% isopropyl alcohol on the rotors, and even replaced the pads, all to the same result - good for a few days, followed by diminished to total loss of braking power over the course of the week. What is wrong with my disk brakes?

https://blixbike.com/products/aveny-electric-city-bike
Tektro Aquila Mechanical Disc Brake, 160mm Rotor
Adjusting the pads is a normal part of maintenance for mechanical disc bikes.

I have a tektro mechanical e-Bike that is ridden with rider+cargo > 200lbs  8 mi/day with 4 steep (> 50 meter elevation change exceeding 20% grade) hills.

I move the adjuster for the moving pad in one "click" weekly when filling tires and readjust the static pad monthly.  I invested money in buying a set of long ball-end hex wrenches, and stopped trying to work a mini bike multi-tool through the spokes to get at the adjuster, it's not really a big deal.

Moving pads in weekly or even twice weekly depending on just how heavy and hilly your idea of "very" is, does not seem extreme.