I bought a little tiny stubby 2-pack of screwdrivers from Walmart that work perfectly before the engine becomes red hot. I put marks on them with a Sharpie so I could index them. For some reason I just couldn't get it right with the short ratchet screwdriver. Also beware - some of the fancy long-handles screwdrivers have a blade that is too short or too wide to work correctly.
I also swear by those stubby screwdrivers, I keep a set onboard at all times...
You do have to be quick when using them, or you roast your hand, but if you fold a piece of cardboard, and slip it in below and in front of the carbs, it works well to prevent hot fingers and burns....
As for messing with them, I've never found it necessary to do, if I built the carbs from scratch myself, as I make sure they are all equal from the start,
I do 2 turns out from seated when using OEM needles, and 2-1/2 to 3 turns out when using K&L rebuild kit needles... they are tapered slightly different...
Trying to use the wratcheting screwdrivers is really a pain, because when doing this you are basically turning the needle back and forth, and listening for a change and that simply can't be acomplished with a wratcheted tool easily and rapidly... most people trying to "adjust" them while running totally mess them up as far as being even, and never realize it.
I built Lobo McClurg's carbs attt the '07 nationals, and when I was done, told him to hit the starter.. it fired right up first rotation, purred like a kitten, and when we put the vacume synch tool on they were soooo perfect I couldn't touch a synch screw without throwing them off... mind you that was because I carefully preadjusted all the throttle plates during assembly.. ( that part has nothing to do with the air mixture screws, just saying.)
The 28 yr old Kawasaki truck "tech" that happened to be onsite, insisted he could "adjust them" better and wanted to mess with the mixture screws, I handed him my stubby driver, looked right at him, and told him anything from this point on you are responsible for.... I did the job right...
Well, he "attempted" to tweak them all back and forth, and never made it better, it actually sounded worse.... on top of that, he had to twist the idle knob a full turn to make it "idle"... @ 1100 rpm
Larry Buck was watching him, and kept looking over at me....all I could do was laugh... and give the kid angry looks till he was "finished"...
After everyone left and went to the banquet, and the bike was cooled down, I went over and checked and re set them all to what I had done when I built them...
The "tech" had them at 1-1/4. 3. 1. And 3-1/4 turns from seated....
When I returned them to my liking, I turned the idle knob back down... so it wasn't idling at almost 2k
Fuel efficiency... bah....