It’s always best to pack ‘for’ the segment of your flight itinerary that has the smallest baggage allowance requirement - baggage allowances on international flights are often larger than domestic flights. Also, be sure to check with your airline to confirm what you are allowed to carry.
Our ships do have laundry facilities, so you do not need to pack clothes for every day. Baggage allowance onboard is 2 pieces per 1 person. Our advice is to be reasonable.
Go to our How to pack page for more details.