How often check or change mechanical disc brakes

[GirishH]

I'm curious—how often or after how many miles do people typically check or change their mechanical disc brake pads?

I've been bikepacking for a while but never really followed a maintenance schedule. A few weeks ago, I took my bike to a mechanic because I heard some noise. The mechanic did a quick overhaul, and I was sent on my way.

However, a few weeks later, while descending steep hills, I started feeling like my wheel might come off. It was alarming, and I thought something might be stuck between the pad and the brake rotor. I removed and readjusted the wheel, but the problem persisted.

Finally, after tackling a few more steep sections, I found a motorbike repair shop in a remote mountain village (there were no bicycle shops around). To my surprise, I discovered that one of my brake pads was completely worn out, which explained why the wheel felt unstable when I applied the brakes.

Fortunately, I had a spare set of brake pads, so I replaced them, and the problem was resolved. This experience got me thinking—how often should one check brake pads during long rides?

Interestingly, I noticed the spring was broken as well, but I didn’t have a spare. I had to make do with it for the rest of the trip. What role does the spring actually play in brake performance?

Once I reached a larger town, I replaced all the brake pads and springs. However, one of the springs isn’t sitting properly, despite trying all the tips and tricks I’ve read or watched online. I’ve even ridden 50+ miles with the spring slightly misaligned, but I still can’t get it to sit snugly.

Does anyone have pointers or advice on this?