I'm just not sure that it really matters. Dak getting 20 snaps in the preseason won't determine if this team wins week 1 or not, nor will it determine if Dak is in rhythm or not. The 1000+ snaps he is getting in camp significantly outweigh the preseason importance. I can see preseason having some significance to younger players or guys new to the organization getting the game day run through to see how the game day process goes in Dallas or the pros in general. Also just for the guys who played at smaller schools who have never played in front of 60+ thousand fans.
Some guys need the preseason, some guys don't. I think Dak has pretty much shown that it doesn't really matter how much he plays before week 1. For the concerns I have about Dak, this isn't one of them.