Is it better for a GC / DB to revise Orig Dur or just Rem Dur if you find out a procurement is going to take longer?

Is it better for a GC / DB to revise Orig Dur or just Rem Dur if you find out a procurement is going to take longer?  (and of course note it narrative - haha) - I have seen only OD and RD required in specs for 35 years when Dur at Completion (or Act) is the most important.  How many times to we have to see OD = 5 RD = 2 DaC = 223 with a giant bar next to it, but no DaC (or Actual Dur) column.   I like DaC more than AD but both get you there.