Dropped elbows

Failure to drop the elbows means that your arms will extend too far away from the body, causing minor joint strain and immobility.

Coupled with a fairly small stance, dropped elbows will radically improve your capacity to move.
Freedom in the joints and spine is imperative in actual combat.
It leads to increased manoeuvrability.

Practice maintaining dropped elbows at all times, all day long.

Your arms can extend from the body, but only so far. And they must always come back.