I don't have the best kick in the world, but sometime before those last 0.11 miles in a 5K, I like to go all out and empty the fuel tank. That leaves me dependent on either having a reasonably accurately measured race course, or knowing in advance that the course is going to be a non-standard distance.
For some reason, I've had a string of races lately that have been off. There was a 10K in March that checked in at 6.43 miles, a 5K in April that came out to 3.18 miles, and then most recently, a 5K that fell short at 2.93 miles. Now it's possible that the GPS on my smartphone was slightly off, as even GPS watches aren't perfect, but I'm inclined to think that the errors in those races were the actual distances, not my phone, because the race times I turned in (and in some cases, those of other racers that I talked to) were consistent with the courses having been mismeasured.
Assuming that my smartphone GPS was accurate, we're talking about mismeasured course distances of 3.5%, 2.3%, and 5.8(!)%. Those seem like pretty significant inaccuracies. The last one was the strangest one of all, as there was a short out-and-back segment in the middle of the race, where it seems like it would have been trivially easy to tack on an extra 0.09 miles to make the distance right.
Now, I'm not an elite runner, and these aren't qualifying races for any bucket-type events, so in the long run, it's not a big deal. But I found the last race in particular a bit annoying because I was pacing myself based on the expected distance, and the end of the race was hidden around a corner, so I basically finished with a very short kick, not to mention a sub-20:00 "5K" time - a goal that I'm chasing right now - that isn't real. I was comped this race, so I can't really complain, but if I'd paid the entry fee, I think I'd be a bit more annoyed - although I guess it would mean that if the organizers use the same route next year and I run it again, I'll be prepared to speed up at 2.7 miles instead of 2.9.