I (personally) always design for voltage drop.
The note about the 5% appears on my drawings only to give me a club for when the VE exercises result in the EC sizing the wire for the load and ignoring the effect on voltage drop.
Before that note was there, smaller wire got installed (to save $$) and the voltage drop was suddenly my problem.
Since the note, the problem comes right back to the EC who installed smaller wire than the design called for. It's headed off a lot of problems since starting to appear on the drawings.
...and yes, there are some lazy engineers out there who don't even bother to run the calculations and just hide behind the 'killer note'.
