Curing large quantity of silicone ... takes longer?

[Delphinus]

Has anyone tried to sandwich a piece of glass onto another with a film of silicone between? How long did it take to cure?

I imagine it's fair to assume it will take longer than say a bead of silicone along the edge or a corner. But if, say, 12 hours later and the silicone is still quite wet to the touch, is this normal?

Does silicone have a shelf live? Or if it gets cold in storage or something can it become ineffective (i.e., unable to cure)?