Holding speed fixed isolates persistence time as the source factor for run length. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
One second gives a four-metre run scale
Hold speed at 4 m/s. Persistence time 1 s gives run length 4 m.
4⋅1=4
Two seconds gives eight metres
The same speed for 2 s gives run length 8 m. Only the persistence time changes.
4⋅2=8
Three seconds gives twelve metres
At persistence time 3 s, run length is 12 m. The diagram is not a sampled random path.