A progessive laying system

Iv been messing around with laying. Basically take 3 6/4 horses and back a £10 treble with bookie. Then bounce to exchange and lay the 1st one for £20. If it loses you make £10. The idea is that it's so difficult to strike a treble your basically laying trebles... What was more interesting is football (half time correct score markets). Back 3 0-0s treble. Lay the 0-0 progessivly..