I've mostly been told to use one 512 map max for lighting maps while textures I ship have a casual working file size of 5 gigs and above for substance painter. Idunno how well they get packaged up as since I haven't played any of the games I've worked on for a while. I can see vertice data taking up a lot but other than some AAA games I don't see why anyone would need to make super poly dense models.