...and, to add to Dick's comment...
If they are perfectly located, small holes may be in a better location to find the maximum pressure drop through the venturii. The rate of feed through the jets is very slow - for a Fox Stunt, it is something like 2 minutes per fluid ounce - so a small restriction isn't that much problem; we can compensate with the needle setting...
I thought the standard Fox Stunt NVA was still two holes...
OS and ENYA single-jet spraybars also have very small jet holes, and run VERY well.
Gag Q: How do you keep the holes aligned East-West all the way around a lap??