How many pieces do I actually need in a luggage set?

A 2-piece set (carry-on plus large checked) covers most travelers, while a 3-piece set adds a mid-size checked bag useful for families or longer trips. Larger 5- and 6-piece bundles exist but often pad the count with totes and toiletry cases rather than additional rolling bags, so focus on the number of wheeled suitcases you'll genuinely use.