Impossible to say.
It depends on the ball and why you're resurfacing it. Full resurfacing removes a lot of coverstock thickness. I'd guess 3 to 4 are the max for a FULL resurface. If you can successfully extract all the oil it absorbs, it can theoretically keep going for a long time.
There is no set formula, that I am aware of.
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"None are so blind as those who will not see."