I found this link which talks about the Syrian air defence (or lack thereof) and there are also links to much more stuff, such as evaluation of air to ground guided missiles, smart bombs, etc.
http://www.ausairpower.net/APA-Syria...eployment.html
**Ok, finally found a video of all things that talks about the Patriot successfully being deployed miles apart and still engaging. Now this is new technology as the video is from 2017, but for game purposes I would say that SAMS should be deployed at will as the player feels.**
https://www.youtube.com/watch?v=Jm_N0xvqZMY
And a very scientific pdf. As stated, it appears on how valuable the target is, and the threat area to be covered dictate deployment.
https://www.sciencedirect.com/scienc...07904X9390086V