I'm sure they would be fine if they were wide apart. It's more about training the commands and getting used to the equipment rather than doing anything that is going to put pressure on growing bones. I've learnt the weaves several different ways, but one that is probably more appropriate for puppies is putting two parallel sets of weaves (alternating) and getting them to go between them. Some have weave straps to guide them, and gently bring them closer together over time so they are gently weaving. Does that make sense?