Now, don't throw the baby out with the bathwater. There are times when the conventional wisdom is right.

If you're tall and lanky, oversized fits can look intentional and add bulk to a slim frame. If you're curvier, a regular fit can skim without clinging, which many people prefer. And if you're buying a tee for a specific event—a community meetup, a concert, a casual workday—regular fit is usually the safer bet because it looks more polished in photos.

Also, if you're between sizes, sizing up on a regular fit can work if the tee's shoulders still align. But that's a fit hack, not a replacement for the real thing.