Before you travel, do carry an extra pair of pants in case you are going for a short journey. Such as an day trip or one night, two days trips. Many people pack light for such journeys and then end up regretting their preferences.
On long journeys, make sure that you have atleast four pair of shirts and pants in your luggage with you.
The days have changed. Earlier people would carry four to seven suitcases for “Just in case”, in case any requirement arises. Now, with a small backpack, men and women are out there to win the world. After that it’s the mother who have to wash their smelly and forever used cloths.