Five feet from the front wall

Okay...what speakers are you talking about?

It’s irrelevant.  Place your speakers where they balance and sound best in your room.  Where you measure them from means absolutely zero.  

@dsper: Yes, measurements are always made from the baffle the loudspeaker drivers are mounted onto. The 5' figure is especially apropos for dipole planar loudspeakers. 5' allows the speaker's front wave to be heard 10ms before the rear wave (sound travels at about 1' per ms: 5ms from the back of the planar to the front wall, 5ms for it to return to the planar after being reflected off that wall), the minimum required for our brains to hear those two waves as separate acoustic events. But that 5' distance is only one consideration in getting the best sound in your room.

It seems like you guys are leaving out some of the equation? speaker ported, front or rear, speaker depth regarding first reflection and room boundaries. I have a pair of Meridian DSP speakers with an option to time align the bass, their blurb states the woofers would have to be several feet behind the rest of the speaker to otherwise duplicate what they do digitally, but tbh I can't hear a difference either way. I do wonder if speakers that use side firing woofers are less sensitive to placement in regards to bass, but you tell me?

Which ever is easier for you to measure. Any formula is alway just a starting point. I can’t imagine where ever you start is ever going to be the end point… frequently not even close.