I was browsing through the CME catalog a while back, trying to find a name for a particular bit when I didn't have a rig in front of me to point to. I noticed a whole section on "optional accessories", which reminded me of a few things that can make a big difference in the driller's effort expended (and therefore the amount of time I'm out there watching the rig). Although I am not a driller and am not experienced in all the mechanics, I've seen enough different crews/rigs/methods that I have strong opinions on the stuff that really makes a driller's life easier.
1. SPT (standard penetration test) auto-hammer. There's a standard for determining soil density: the number of blows it takes to drive a 2-inch split spoon 6 inches using a 140-pound hammer dropped 30 inches. You can have a guy use a cathead (spinning wheel that rope is wrapped around), which means he is essentially yanking on a piece of rope and allowing it to drop over and over and over again, or you can use an auto-hammer and just pull a lever. Not only is the former method laborious and exhausting, but you're also depending on the driller to drop the weight at just the right height every time.
2. hydraulic breakout wrench. A driller cranks on and cranks off various threaded rods all day long. Crank on to go down the hole, crank off to come back up. And if you're doing any spinning (which you are with most drill methods), it will take a lot of effort to get the rods to first separate ("break"). Without a hydraulic breakout wrench, every 5 or 10 or 20 foot section has to be yanked at with the drillers manning 2 giant wrenches and cheater bars. Not only is the hydraulic wrench a lot faster, it's also safer.
3. Pipe carousel (generally found on larger rigs). Rods are mounted on the carousel and when one rod is in the ground, the carousel rotates and another rod is available immediately. Without this, the rods are individually picked up and swung into place.
4. Mud pump. A driller is going to pump a lot of grout, and possibly drilling mud. Better to have everything on board and sized properly rather than using a succession of trash pumps scattered around - a good rig-mounted mud pump can handle anything, including nuts and bolts.
I've seen a lot of cheap, jury rigged drill rigs. I realize it's easy for me to comment, because I'm not the one paying for them, but minimizing the amount of labor and manhandling of large/heavy equipment is not only faster, but infinitely safer.