I burn at 1/4 the maximum speed my drive allows because in my experience although *some* DVDs come out okay at the maximum burn speed, quite a few do not. This is using Verbatim DVD+R (or another brand that uses the exact same manufactured disc with their label on it). So typically I burn at 4x and never experience a problem.
This was after a year or two of burning DVDs using the maximum speed, and probably four years burning CDs at the maximum speed. I had read that advice (to burn slower) but didn't heed it until I experienced it myself. If it's worth having, it's worth having at a reliable quality, IMHO.
rule of thumb i use is burn the media you have on the lowest setting the burner supports burning to that media at, might take a bit longer per disc, but you will get a good steady burn, and you will make your drive last a bit longer
I agree with carpo, it will also make the disk readable by more drives. Something else you have to think about as well is that just because the burner is 22X doesn't mean the write speed will be that. You have to get a disk that can be burned at that speed. I have a 16x burner with 16x discs and it has never burnt at that speed when testing it at max speed ...