Stan Pac told us we could come and walk ANY TIME, including the "pre drywall" walk.
My hubby was the one who came to look at the house as it was being built. When he went on the pre drywall walk whoever went with him explained a few things that were new to us, maybe common knowledge to others (certain walls are completely covered in wood before drywalling as opposed to just studs for earthquake stability, location of sprinkler pipes and some other area that had extra wiring for the router).
We have pix of just about every single wall and celing predrywall so we know approximately where the studs are, which way the studs are laid in the celing and where we should avoid trying to nail into (exterior master bedroom wall and pantry wall, not adjacent to fridge, sinks, toilets or anything else needed for water for instance have a big water line which we wouldn't have known if it weren't specifically pointed out to us).
Last week, the head of customer service saw me staining some wood in the garage and asked what I was doing (making a new headboard) and I showed him the mudroom we're working on (took out a cabinet in a cubby near the garage). I mentioned we're putting a false front on the drywall soffit and extending the cabinets to the ceiling because we wanted to have the bench farther out than the soffit goes so we can have retractable doors on the area above the bench and still have enough room to sit so it hides any mess) and he said if we want to cut into that soffit it would give us more space above and if we're worried about what is inside we can go to any production home and see what's there....... just let him know when we want to come).
For us, those pix are majorly worth it as we have lots of work done after COE. and it saves us lots of time and effort trying to figure it out what plumbing/wiring is in the wall with dry wall in the way.