Hoping to break 17 for a 5k in a couple weeks, standalone 5k PR was 18:01 a year ago but I did a 17:50 mid workout a few weeks ago, currently averaging 35-40mpw as part of a total ~15-17hr/week triathlon training. Two recent workouts were 1) 5mi tempo @ 6:10 pace, 4' rest, then 5x1k (3:20, 3:18, 3:17, 3:17, 3:13) with 2' standing rest between done last Wednesday; 2) 4x(800, 1:30 rest, 1600, 3' rest), times were 2:42, 5:24, 2:40, 5:21, 2:41, 5:25, 2:41, 5:23) today. Both workouts were also done after a hard 3-3.5k swim in the morning as well if that counts for anything, so not nearly fully rested. Based on that I think it should be possible, but would be curious what you guys think!