Does that work reliably? @MadCow2357 mentioned that other factors could cause the result from rolling the vehicle to be inaccurate.
*shrug* It works pretty well for our buggy, it depends on how your buggy works
Like LMN said, it depends. If you are just testing your buggy out, and getting a general idea of how many rotations it needs to travel between 9 and 12 meters, this is fine. Totally works. However, I wouldn't use the data from this to set your brakes for competition - it doesn't account for the other factors I mentioned, and it is better to test for the individual distances separately. Makes sense?
In my experience, I suggest you to just test it. Once you finish your vehicle, start testing it: start my winding it only a little, then wind more and more until your desired length. Once you know, let's say, 50 winds is approximately 12 meters, you can calibrate your car more accurately from there.
Using the data you get from that, you can start testing other distances: 9, 9.5, 10, 10.5, 11, 11.5.
Just to name a few: skidding (big), wheel slippage, oversteer, understeer, drifting
Skidding is the same thing as where slippage, and drifting is an effect of uneven wheel slippage on either side of the car. So really the only factors there are are skid and in what curve/line you push back in (steering or curvature)