Rower here. And I engage each gear. I'm almost certain it's slower, but over 30 years ago I learned to drive a stick. Mama(parents were separated) had me going through every gear. Can't heel-toe for a lick either, but in my videos and trackside, folks can't tell that I don't. Can't practice because my only stick is my track car. Won't drive the Miata publicly unless I absolutely have to- wife's plates read: "WTI BITI."

But as Billy stated, different strokes for different folks. I've been told a) never have your car out of gear in case you need to "GO!" and b) you can slow a car down more quickly with it out of gear. If you ask me, something's got to be compromised between the two. I think(purely opinion here) if you're racing, you'd better be in gear. If you're putting around in HPDE or TT, maybe you can get away with being out of gear.

I've enjoyed the thread.

 

Everything that needs to be said on this topic Billy has said.

To summarize:

-If you are worried about time, focus on your braking and don't worry about how downshifts are accomplished.

-If you've got the braking down and are worried about your synchros, man up and learn to double clutch. A proper double clutch doesn't even use the synchros. You should be able to slide the gear right in and let your foot off the clutch immediately without upsetting the car if you do everything right.

-Practice on the street. Your first focus should be maintaining proper brake pressure while you blip, since this affects lap time.