Do you need to meditate for a long time for it to work?

No. Short sessions genuinely help, and consistency matters far more than length. A few minutes most days does more for a calmer, steadier mind than a rare long session. Even one to five minutes can settle your nervous system and reset your focus. The best length is one you will actually keep returning to. StillMind adapts sessions to the time you have, so a busy day still leaves room to practise.