We keep our bimini and enclosure up year round. Especially in the summer months when you almost can't be outside without shade. We use our FB all the time, and we love our enclosure. When we lost the bimini and enclosure in Hurricane Irene we did one trip without them. It sucked, even though we were in the Bahamas in November.
When it is hot I roll up the curtains, though I wish my bimini were set up so that I could just "swing" up the curtains and secure them under the top, less wear on the strata glass than rolling.
It keeps my FB a lot cleaner, and keeps the varnish looking good longer, when I use the enclosure.
Our weather is different than other parts of the world though, so different people do different things, I guess.