Very true... when I changed the front pads on my MTB I took it for a quick spin to make sure they were fitted properly and the first time I applied the brake it made almost no difference at all. That caught me off guard, even though I should have known it would take a few applications for them to really take effect.

After that I rode half a mile or so down a quiet rode squeezing the brake on and off every second or two. Then when whatever coating was on the brake pads had worn off I squeezed the brake and came to an almost instant halt, at which point I was satisfied in a job done right.