Well, if there’s some slack and you tighten with the wheel hanging down then you could hit a bump on the track and knock the slack up the other way. If the wheels on the ground when you tighten things then you hit that same bump your set up is not going to move. Probably doesn’t matter too much in todays modern world, just a habit left over from the old days.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience