Piping orthos

In our recent projects, we have proposed to entirely strike out preparation of piping orthos (or piping general arrangement drawings) especially if the project and client are looking for opportunity to reduce the cost. As you mentioned, if the 3D model (with iso drawings) are handed over to erectors, all the necessary details required can be taken from it. In the near future, I can only imagine that 3D model of the plant itself can be locally downloaded and viewed with same functionality as high end 3D model viewers (SPR and Naviswork) in a platforms like tablet and smartphones.

I would agree that fully detailed Orthos are a waste of manhours these days when piping is detailed in 3D Model and isometrics extracted. Orthos such as General Arrangements, depending on your terminology, are still a class 1 document in most client specifications meaning they have to be approved by client which can affect schedule, in current project I have managed to 'downgrade' to class 3 same as Isometrics meaning issued for information based on we review all lines in 3D Model Review.
However I like Anton's suggestion of providing with minimum dimensioning which in construction phase will still allow to easily locate the pipe(s) and visualize the adjacent piping/equipment and then use the Isometric for fully detailing.