if you mean eagle one wax as you dry, i'd say it provides water beading for at least 2 weeks, sometimes a month, depending on the conditions.
if you spray it on an existing (paste) wax, it will certainly help.
i generally wash my car twice a month and use paste wax every other month, and waud has no problem keeping this schedule. if my car is dusty but clean i use detail spray and then waud.
in the winter i will just run the car through a touchless wash, then take it home and waud it in my heated garage.