NO, THEY CANNOT
Unless you have some kind of muscular or joint dysfunction which require leg lefts to help - please please STOP wasting your time with these. Don't get me wrong - I loved my Jane Fonda VCR workouts in the 80's too, but sometimes, (like g-string leotards with leg warmers), it's good to change. As a wise woman once said to me, "Toner is for printers. I lift."
If you are trying to tighten up or reshape your body, the only way to do this effectively (assuming your eating habits are on point) is through full body resistance training at least twice per week. If you like doing leg lifts, go get em, but if you are trying to create change, please spend your time in the weight room. And as always, if you don't know a thing about strength training, ask a physical therapist that you trust for a referral.