I recently saw where resellers were discussing how fast they could list an item. This seems to be a topic often discussed.
While being slow is not necessarily a good thing, going too fast can be a bad thing. You take short cuts that could lead to missed keywords and item specifics.
If I can do a listing in 10 minutes start to finish and you can do it in 8 minutes. Great. I will work an extra few minutes and possibly have better listings.
Find your pace. Do a good job. And leave the racing to NASCAR.