WooCommerce Quantity Manager has advanced logic to ensure that the correct quantity rule is always used. For example:
You can mix and match rules, for example by combining quantity and value rules to ensure that customers buy the correct quantity and spend the correct amount.
If you set a default quantity that isn't possible due to your quantity rules, then the lowest possible quantity will appear as the starting value instead.
The WooCommerce quantity plugin has advanced hierarchical logic built-in. The global quantity rules can be overridden by category rules, which can be overridden by product-level rules, and so on.