Bob, that's true in most cases.
The Westport (CT) Roadrunners Summer Series, which will celebrate its 50th year this summer, was originally designed as progressively longer races for summer conditioning for HS athletes. 3-4-5 miles etc. The courses were measured with the town police chief's car.
Years later when they were more accurately measured, the distances were determined to be more like 3.1, 4.2, etc. but so many times had been recorded the distances were changed to more accurately reflect reality. I measured all 10 courses to USATF standards back in the late 90s and achieved even more accuracy, but the names remained at their one- or two-decimal places.