The flier on the system (?) I am following related the following to me when I asked why his birds were two up and mine 1. Feed, genetics, weather? He said, most are up two. Some have not dropped a flight. Other 2 are up 4. Talking 40 young birds. All early bred. Said it happens every year. Being a lazy man system variations do occur. BUT! If the lights are on 15th June all moulting stops. Or is slowed down to nothing. They drop a seventh flight, middle two tail feathers go. No longer any good to race. The fellow in question is a super flier with many wins and awards. Also initially spent a fortune on imports years back. Into eye sign heavily. But within his own family. In a nutshell. Genetics, eye sign, feeding etc,. One cannot asses by any quality. A good bird, exceptional bird, can com from any pair.