the A380 rosters are 3 return flights
Fraid not - can I ask if you saw actual rosters or just the Stage 1 lines?
I've just had a look through the published 380 final
final 
rosters for March (both captains and P2s) and most full time pilots who don't have any commitments in month such as leave, Duty Free Week, Training, etc, seem almost all have 4 trips on their lines. I'd honestly say if you are in a fulltime month with no "blockers" in BA long Haul you can expect to probably operate 4-5 trips, regardless of fleet.
Going back to the 380 for a minute don't forget the 380 is not just doing the ultra Longhaul stuff such as SIN, it's picking up some of the lower credit hours, lower flying hours stuff at times such as MIA and IAD (and there are rumours of it picking up one even lower flyiong/credit hour destination).
Dare I ask if where you heard about this points for trips scheme?