Yesterday in downtown Detroit I was not able to use my usual calibration course because there was an event going on at its location. So I had to use another cal course that I measured in 2017 that I haven't used in a very long time.
The endpoints of this course were both at the edges of sewer drains, but when I got to the course I could see that there was brand new concrete around the drains, and I became concerned that the drains themselves had been moved. So I pulled out my measuring wheel and walked the course with it. Sure enough, the measuring wheel said 260+ meters, and the course certificate said just a little under 258 meters.
So next I pulled out my steel tape and nails and spent the next 40min or so taping the course. My steel tape measurement came out 45mm longer than the course distance on the certificate. My measuring wheel had a 0.7% error for a straight-line measurement!!
Moral of the story: Next time somebody tells you they "wheeled" a course, take it with a boulder-size grain of salt.