I would squeegee them every time and spray them with vinegar on a regular basis as well. Not sure about RainX but thought other people have commented that it did not work so well.

A lot of shower doors (depending on brand) have a coating already applied. Squeegee after each use and you should be fine. Vinegar will work if your seeing water spots after squeegee. I get mixed reviews about the rainx, I think hot water may break it down. I found this on another site a while back.....8 oz. (1 cup) of vinegar 8 oz. ( 1 cup) of Liquid Dawn dish soap. put it in a spray bottle and use when glass gets "foggy" or soap build up ect.

Squeegee each shower, spray vinegar on in between but if any build up, spray 1:1 vinegar and dawn, let sit, rub it on, rinse and squeegee. Works great! Do NOT use windex! I have a condo and this has worked well since getting the new glass doors.