I think it depends on how you're travelling. If you're staying in hostels and moving locations frequently (v common for solo travel), walking/busing instead of uber/taxi, using just one bag is peak. But if you're staying longer or you have your own room, getting rides places etc, then it might be worth having more clothes and dealing with lugging your suitcase around occasionally.

Doesn't even need to be a suitcase, a big duffel bag can hold just as much clothing and be more convenient for carrying around, although you still need to check it at the airport.