I've got three of my Star machines set up with the bullet feeders and use tubes that hold from 50 to 60 bullets, depending on the length of the bullet. I can go through a tube of bullets in about two minutes or less, if I really get on it and want to see how fast I can size and lube. I just normally set a pace and go with that, though.
Of course, there is the time it takes to fill tubes, but I've made a little rectangular box with V-grooves in the bottom for filling the tubes. Put a handful of bullets in the box, shake it a little, orient the few that fall into the grooves backwards, then place a tube in the hole in one end and tip the box and tube so the bullets run into the tube. Repeat as necessary, and I do it while watching the news, or some silly TV show...
Hope this helps.
Fred