The following one-liner MAXScript from Grant Adam has saved a ton of time while working with RPManager in our Arch-Viz pipeline.

RPManXref.captureAllXrefPassesIfNotAlready true

Simple little line of MAXScript that is incredibly powerful. Let me explain...

One of my absolute favorite scripts for 3ds Max and probably the one that's used the most day-to-day is Martin Breidt's "Incremental Save". It eliminates a ton of headache when dealing with lots of revisions to Max files over a long period.