Ive been using marvel lash extensions for the past 5 months, but the lashes seem to be lasting different lengths of time on each person. Some will last 4 weeks sometimes only 1 week. Is there any glues which would last longer or any tips on application for making them last longer? I make sure the clients remove all make up with oil free cleanser, and give them correct after care advice. I just cant seem to work out why sometimes they last longer than others??