Mike wondered how I can lay out 300 m in a half hour, single-handed.
The trick is to traverse the cal course only once, not twice. I use a tape that is marked with metric scale on one edge and decimal feet on the other edge. By reading each, I get two measurements in one pull, with the readings not expected to agree. The same procedure could employ two tapes hooked over the same nail. By having the tapes use different scales, this reduces the chance of making the same reading mistake on both measurements.
If I should make a reading error I will not find it until I work out the measured lengths upon completion of the taping. This is the reason I don't pull out the nails until I have checked the work.
When one measures in both directions, the memory of the previous reading is gone, and it is unlikely that the same reading error will occur.