so it is a "slip and lock", but all the notices in the manual i can see several spots that could allow the failure.

the cylinder and adjustment rod are on the top, only the ebrake is on the bottom which means when the pads push on the drum only the top pushes out. The bottom only pushes out when the ebrake is applied. (cant stay out because the rod is on the top.) That design also creates the adjustment rod and nut as a pivot point, and the pivot point mores out with wear. but your not using the whole pad, not really, so wear would not be very significant overall.

It says several times to press the brakes until it stops clicking, And that the nut can not be tightened against the back of the rod. This would prevent it from adjusting at all. I would probably not put it against the rod as the procedure says, i would leave a thread showing..

well honestly i will upgrade to disk.