It depends more on the item than the calendar

There's no single rule for every garment. What you wear against your skin, how much you sweat in it, and how structured the fabric is all change how often it actually needs a wash.

• T-shirts and underwear: after every wear.
• Jeans and outerwear: every 4–6 wears, unless visibly dirty or stained.
• Sweaters and structured jackets: every few wears, since frequent washing can wear them out faster.

Over-washing has downsides too

Washing clothes more than they need can fade colors, weaken fibers, and shorten the life of a garment — especially delicates and structured pieces. Spot-treating a small mark is often better than a full wash.

A simple rule of thumb

If it smells fresh, looks clean, and hasn't touched anything messy, it can usually go back in the wardrobe. When in doubt, a quick air-out is often all that's needed between washes.