I propose that this be changed to “5 or 6”. At Cranberry Days, I noticed that 5 studs actually fits the best and tends to lessen the side to side shimmy as a car travels down the track. Plus 5 wide can be more of a building challenge.
2×5 bricks with axles on both ends are pretty rare… sounds like we designed/built our track poorly.
Also, is there a weight limit?
I think the width and length requirements are restriction enough. I’ma go #buyalltheBoatsThatReallyFloatWeightBricks on Bricklink right now!