Shademap for stereo 360 animation

Doing 360 animations at the moment and the insane render times for dual 4k to get stereo is killing me leading me to shademaps after forgetting about them for a long time.
Is it one shade map for the entire scene if you are doing say a 30 second fly through sequence?
Thanks

ok looks like would need to generate one every frame then re-render that frame using the saved cache excluding the glass.
can they be precalcd with AA pretty much off and filtering off? cant quite get my head around the usage