It actually could do ok if you used a heat sink in the glycol bath, and a fan to circulate the air.
@Nater pretty much nailed it--generally air isn't enough to chill the glycol mix enough, at least not very fast.
I actually did a glycol chill bath in the upper freezer compartment of my big ferm chamber. It actually worked fairly well, and if it could work in there, it would work in a chest freezer, in fact, probably better. I'm attaching a pic showing how I tried to use a copper tube and an aluminum (DIY) heat sink to enhance heat transfer to the air. It worked, after a fashion.
If I had to do it over again, i'd probably look into a chest freezer. Might not have worked--I'm very space-limited--but it's far cheaper.
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