Per direction, not per individual flight segment — exactly like a real network carrier.
- Connecting itinerary (with a stopover): your bag is through-checked once and rides the whole way. You pay one baggage fee for that direction.
- Outbound and return: those are two directions — so two baggage fees. You still pick your checked baggage only once in the booking flow; the displayed price is already the honest total for outbound plus return.
Seats, by contrast, are charged per flight, because a seat is tied to one specific aircraft.