Deputy Captain is nice, we used to say we hire captains-in-training, pretty much the same thing. Anyway, take offs below 400m RVR and CAT II/III approaches are not allowed from the right side so that is allways the captains duty, everything else should be shared equally and i've never had any argument about how many sectors to fly with any captains. It is of course allways the captains final decision, but most of them happily delegate it to their deputy captains.
We usually do 3 or 4 sectors a day shorthaul W-pattern style, so flying every other leg would lead to one allways landing at the homebase, most of the time one flies the first and last sector and the other one the two sectors in between, but of course sometimes one does the first two and the other the last.