I'm not sure i've ever really seen this discussed on here but I'm sure its something the system aficionado's can provide some answers about.

Basically i've found it easier to create some lay systems have currently have 4 that i'm forward testing and having quite a lot of success with so far. My question becomes that say you have a suite of successful lay systems can you then utilize these to also create backing systems since you obviously do not want to back the lay selections as you have a negative expectancy on them?

Seems fairly logical to me and I don't see an issue with it but just wanted some confirmation from those you have been doing system backing/laying for a longer amount of time successfully.

The reason I ask is i've done some backtesting using really basic rules, for instance backing the top weighted horse that isn't a lay selection and the results are very encouraging.