I don't change the 'main everyday' clothes too often for most characters though there is one character that pretty much has a different outfit each chapter (she has a set wardrobe that she rotates through, just haven't been enough chapters to cover them all and start her wardrobe rotation again), because that's just part of her character, she hates wearing the same thing more than one day in a row.
Outfit changes are more-so representative of the story and situation than reality.
1) Small clothes changes for temporary situations like pajamas, gym clothes, formal event, uniform.
2) When seasons change to accommodate for the weather.
3) When a significant amount of time has passed from the last chapter/scene.
4) A significant character development change within the story.
Also some characters will have layer clothes such as a jacket or sweater, and there will be scenes they will be without it depending on the scene and location. (to add to that the main character changes/styles his hairstyle when outside of the house)