Here is what may be considered a really dumb question.

Please keep in mind that we are currently living up North...
Over 20 years ago while living in Tampa, garage screens did not exist (to my knowledge), so I made one for a separate bay in a three car garage so I could use it as a workshop. It worked out fairly well, but was very hot in the daytime

so I don't know that I would do it again. The screens that I have seen in TV seem to cover all the doors, and I wonder how well they really work out.
I told you it might sound like a stupid question, but I really would like to know
why people have them, and if they are not more trouble than they're worth (assuming you have to move them every time you want to use the garage for you car or golf cart). I'm sure there are a lot of really good reasons... please enlighten me. Who knows, after being educated, we may end up having them again when we finally get to TV. Thanks!