I don't know if you do any fiberglass work, but most resins are what they call "air-inhibited". The reason for that is so you can add more resin on top without sanding... and it will bond chemically.
Body fillers use a fiberglass-type resin with filler added. I suspect they all have a surface that dries more slowly for exactly the same reason.
I haven't used all brands (obviously) but the difference may be that some are prone to dry more slowly, due to differences in the formulas. Cold weather, of course, would slow it down even more.
If it's a small area, you might try a heat lamp... but don't get it too hot!