As a fellow "upskirter" I can empathize (and sympathize) with your predicament. The point of the skirt is not only that it reveals the calves but that it is accessible to the hands (if the man knows the lady well enough or wants to know her better and thinks that he can get away with it) and that with proper guile and perseverance a man will be rewarded with a view of the inner thighs and knicker-gusset. Luck plays a part in this as it does in everything else in life, of course. Sometimes, though, it's easy to feel that womankind is just not playing fair. One example is the short-skirted, bow-legged ladies who have us fighting our way through crowded trains possibly depriving old and infirm men of a much needed seat in order to obtain the perfect position to examine the knickers. Too often the short skirt is a tease without due reward since the lady has practised to perfection the skill of uncrossing her legs while simultaneously rising to her feet
Mind you, there are the occasional instances of outrageous good luck!