I guess it's all a bit random. I have a TT bike with the same sealant that I've been using sporadically for about 4 months. Sealant is still in good shape. As an aside, the tires with the gelatinous sealant are Pirelli P-Zero Race. I have them fit to Stans Alpha 400 rims, which have a 17mm internal width. They never "sealed" well and would lost air far more quickly than my Conti GP5's will. I re-set them a few times, but they never sealed they way I would want. Do you think the tires themselves may lead to early drying to the sealant?