A lengthy exchange at Autodesk's User Forums about this subject reminded me that I've meant to create a short video to describe how they relate to each other for quite awhile. This morning I saw our cutting boards drying next to the sink and realized they could serve as metaphorical coordinate system planes (Project and Survey) work in Revit. I am curious if readers find it helpful.
The original post at the forum dealt with a few projects that had been modelled very far from Revit's Internal Origin/Startup Location. I looked at one of the project files and found the Survey Point and Project Base Point had been moved very far away while unclipped. The modelling started there, really far far away. They started to experience some of the negative symptoms that can occur and started looking for solutions...thus the original post. The short answer is they needed to move their model closer to the origin. No other way around it.