I think you can learn alot from the videos at the bottom of the page on this website (speed stringing competition).... cant say anything about the machines.....but the videos are worth watching for people looking to speed up their time...
Tips for speeding up time... dont drop the end of the string while doing the crosses... keep it in your hand... otherwise you just fish for it all the time.
If you are 2 piecing a "normal" frame... just cut the string in half before you start... save time installing mains.
GET ONE OF THOSE EXPENSIVE STARTING CLAMPS! I know they dont seem cool... but you can double it up by your first clamp to get the string going (good for people who have touchy clamps and waste time readjusting them... or making them too tight.... also .. for those of you who dont know this already... those little holes you see in the clamps... they hold a chunk of string that you can loop around..... what this does for you is allow you to tension the "stub" of string that wont reach the tension head. THIS IS THE MOST UNDERRATED thing you could own if you string a number of frames... the clamp is strong enough to hold the string while the extra string looped from the clamp will reach the tension head. I know that there are experienced guys on this forum that can attest to the usefulness of these clamps. I try not to measure wrong and therefore I hope to never use this clamp... but if I have to use it once it was worth it...
I'll add some more later..