Locked savings plans were built to limit withdrawal till they mature/unlock. They only automatically unlock on the withdrawal date specified while setting up the plan.
Invested (or locked up) funds ensure disciplined savings needed to help your goals materialize.
They are invested into financial instruments that mirror the duration specified and so withdrawals can only be done as soon as the plan matures/unlocks on the withdrawal date chosen. That way attaining your goals is made easier 💪