My y/birds are left together at all times. I find that healthy y/birds are always busy in the loft, fighting for perches/territory, pinching nesting material of one another and the like. These are motivating themselves without any help by me. I will try a trick or two when the longer races come around, adding eggs to nests is a favourite of mine. Races under 150 mile I'll add popcorn maize to their feed at about 33%, races longer than 150miles I'll start to add safflower also.