If you are doing more than a few you will have to reheat the water. The only reason it wouldn't work for at least a couple is if it can't hold a few gallons of water over 159 degrees.
You can heat water on the stove top too, but you need a thermometer and then you have to carry it to wherever you are doing the deed.
I don't know where 159° came from above. Scald temperature ranges from 142° f to about 165°f. Hotter temperatures within this range scald a lot faster but leave the skin more brittle, and it will tear more easily. If you are good at hand plucking, that's not a terribly big problem. If you are using a plucker, the skin will look like you dropped it in a shredder if scalded at hotter temperatures. When I was using a plucker, I always tightly controlled my scalding temperature between 145 and 147° f.
