Years, probably. The amount of wax you apply is so minimal that you'll hardly notice its being used.
I have an 8 oz jar of Souveran since 1997 and it's maybe 1/3 used. I've detailed 10-15 cars with that amount.
I applied 2 coats of S100 to a Dodge Ram quad cab and a Jeep Gr. Cherokee and I can't tell if any wax has been used.