How quickly do you need the fence done? If you take your time and make sure of your holes, it's just a matter of doing them one at a time. The hardest part is getting each hole lined up in a straight line. Drilling the hole where you want it doesn't actually happen with a 3pt post hole digger. They don't go down straight and if you hit a rock or root while going down, your hole will move because of that. I use a 12 auger and figure that half of the holes that I drill will need some adjusting with my clamshell digger. Some holes take more then others to adjust!!!!
I less then a thousand feet to go on my front pasture and just work on it when I get the urge. I'm in no rush, so it's not a big deal. I can do ten holes and call it a day, or I can do more. My expense is the materials, so that dictates how much I get done more then anything else. It's all cash, no debt, so no worries.
Eddie