I was involved with a large project. I ended up laser scanning the building in a couple days capturing the building in full 3D using a FARO Focus3D LiDAR. The contractor compared my scans to the Revit BIM model from the architect and realized there was a big problem. The Revit BIM model was created based on measurements taken manually and then all the engineering based on that model which means they were wrong too.
I mean this how we have always done it in the industry. We would send out junior architects and engineers to grab measurements in the early project work and inevitably we would need another dimension and again sometimes multiple times we would send the junior staff out to the project site. It was highly inefficient and not highly accurate when we need all the accuracy we can get.
So in this specific case the people took measurements and missed some and also made some assumptions. Readers, never ever assume one column to column is typical in an old building or old part…