I never find a need to wax unless it’s super arctic cold and getting no glide, but mostly it’s all about spring time. When snow starts warming up and becomes a suction cup on your ski bases, time to put on plenty of spring wax.
I don’t do much to my skis but I also have a $250,000 robotic tuning machine named “The Hulk” in the shop, lol. That thing is nuts.