I once mentored a recruit (Alpha Battery, 21 SA, mono intake, circa early-198

who timed 5:51 or thereabouts. Can only recall his surname - Seow - now but otherwise it was a vivid competition between him & 2 others (an Indian recruit from another battery, plus my new BC officer Mike Yong) to see which of the 6-minute runners was the fastest.
My own best was a 8:03, a highlight of my NS stint considering I was Pes C (obese) & ran my 1st-ever SOC in 15 minutes (got stuck at the monkey bars, my nemesis throughout Tekong). The irony is I was more or less a 10-minute runner as a NSF, then got attached to Temburong Jungle Training with 6 SIR for 5 weeks, then surprisingly ran a 8:56 timing - with little loss of breath - on my return. My then-unit only ran 2 more SOCs before it ROD'ed, & I found myself improving by 20-second blocks each time as I pushed myself.
It all went downhill from there. With the extra half-year to serve out. I was attached to Arty Training Cadre for 3 months & then mainly clearing leave & off-in-lieus during the remainder days. My ROD SOC timing declined back to 10:05.
P.S. To be fair, I ran with the Carbine rifle & not the heavier AR15.