What could happen if we set up Primary leg on each leg of Itinerary

Hi!
Maybe somebody knows what could happen if we switch on Primary leg in each leg of Itinerary.
The matter is that we need to have definite Equipment group on our Itinerary, so we set up Primary leg on each leg.
Our steps:
1. We need to have a definite Equipment group on Itinerary
2. We choose optimize equipment in first leg
3. We set up Primary leg on each leg of Itinerary
Then we have what we need. But we are afraid of something else could happen.
Maybe someone knows what else depend on this parameter.
Thank you very much in advance.