Gary..
This is the requirement you are refering to...

(6) Within 24 calendar months before the flight has--

(i) Made at least three actual or simulated tows of a glider or unpowered ultralight vehicle while accompanied by a qualified pilot who meets the requirements of this section; or

(ii) Made at least three flights as pilot in command of a glider or unpowered ultralight vehicle towed by an aircraft.

this is for maintaining currency, and the operative word is "or".
Since I am an active glider pilot I went nearly 15 years before I ever did another checkout for towing, since I always remained current by making three flights as PIC of a glider. Most tow pilots will get current by doing 3 tows or simulated tows with another tow pilot.

Brian
CFIIG/ASEL