To claim the franking credits, you must satisfy the ‘45 day rule’ (look it up). If you flip your shares after a week, you wouldn’t satisfy that particular rule.
You also need to remember that if you hold past the point where you are eligible to receive a dividend, you are then selling those shares ‘ex div’. The market is generally fairly efficient to adjust downwards the share price to reflect the fact that the shares are now ‘ex div’.
