The other day I was watching a video of a guy changing brake pads, and the first thing he suggested was opening the brake fluid container to remove some fluid with a syringe. This is to avoid spillover when one pushes the pistons back in place, provided one topped-up the oil as pads were wearing down. This got me wondering.
I've always used the brake fluid level as a first-inspection indicator of the wear of my brake pads. As the level drops I take a closer look at the pads to see how much "meat" is left on them. For this reason I rarely top-up the brake fluid. I always assumed that given a new disk and new pads, filling up the container to the required level ensures that there is the enough fluid for correct operation of the brakes. As the fluid goes down, the brake lever gains a bit of play, which I usually counteract by using the appropriate lever regulation system.
Is this bad practice?