Actually, our SAMs were never static for more than 12 hours, and even the huge early warning radars were modded to be semi-mobile. A static SAM site is a wasted SAM site. With enough cruise missiles to spare, they will fall and who's protecting you then? For round'o'clock protection, use multiple sites. With a well trained crew, dissasembly takes around 15-20 minutes, and truck stop to opperetional is up to 30, but can be less.
And as far as protecting an objectve - you can forget about that too. Rather, keep the objective itself mobile if you can. If you can't - forget it and move along, don't waste resources. (oh, they plowed empty bunkers day in and day out. why - I do not know)