Cutting corners at practice teaches your body the corner.

Your body cannot tell the difference between practice and the real thing, so it learns whatever you repeat. A drill done at eighty percent installs the eighty percent version, and that is what comes out under pressure. Pressure does not lift you to a better version of yourself; it drops you onto what you rehearsed.

Pick the one thing you habitually shortcut: the last few metres, the follow through, the stretch at the end. Do it properly every time for two weeks, even when nobody is watching. Shorten the session before you shorten the rep.