Convert to mesh, and Ctlr-J for all assets?

At this point, are you converting to mesh, applying modifiers, joining loose parts for most assets? We did some of that with the buildings and signs. Traffic lights seem like a good candidates. Vehicles, HVAC, lamps, sky lights all seem similarly simple to me; I have a 'probably can't hurt, maybe it even simplifies' mindset. Kent highlights roof-access and water-tower as exceptions. Exceptions don't make the rule. Later, he delicately suggests that we put everything in its own collection. It looks like most things are a single object, at that point. So, direction please!: What are the guiding principles here? What should be converted/joined? Everything except roof-access, water-towers, and parametric-parts (this is my guess)? Does it matter, since we're staying inside .blend? What good nugget didn't I ask about? Eric