Artificer, My experience is the same. It might help to keep it in the freezer though!? I'm just about absitively posolutely certain that acra glas gel and Smooth On are the same thing.
Well, I have never frozen Accraglas deliberately, though it happened a couple times on me. In my old, separate garage shop, it was not heated all the time in the winter. I would fire up my heater when I was out there. A couple of times I left the Accraglas out there when the temperature dropped below freezing and all my epoxies and glues froze. It took a few days for the Accraglas to thaw and "normalize." (Took longer for Marine Tex and it hurt a couple other types of epoxy glues I use.) After the Accraglas thawed out and normalized, it set up properly for the next month or so until I used it all up. I buy Accraglass in the 8 oz tubs of resin and hardener and go through two or three such kits per year.
Since I order so much stuff from Brownell's, I decided to give their Technical Staff a call on whether freezing it will harm it or make it last longer. They said freezing won't harm it, just nuke it in the microwave for about 5 seconds at a time, or have it sit (sealed in the containers) in warm water until it is soft enough to blend.
They also said freezing it would not make it last longer. They also agreed to try to use it up in not much more over a year - if that long. I also asked about Smooth On and they didn't know what that was, either.
After those two experiences with freezing glues and epoxies I made up a special cardboard box of my glues and epoxies and kept them in the house in the winter and only took them out to the garage when I was actually going to use them. Then I would bring the whole box in the house afterwards.