I've seen you recommend time release I THINK in some products.  I can't find how these work. I would really like to know - there is a product my derm's "medical esthetician" recommends - retinol, skinmedica, $$$$$$$ (esp compared to generic Retin-A).  What makes something "time release" and how does that work?  BTW, I don't think the skinmedica site touts that product as time release, but my doc's esthetician does. Haven't purchased yet.