Here in Australia the underlying legislation and case law only allows you to take personal leave in specific circumstances. Generally, because you're unwell, an immediate family member is unwell and you're caring for them, or due to an emergency. Specific companies might relax those requirements but they can't make them more arduous.

Employers can ask for reasonable evidence that you met one of these criteria. For example, they can ask you to obtain confirmation from a Dr. If you go to a Dr and ask for confirmation and merely say "I feel a bit worn out and just really needed a few hours to unwind", they will give you the confirmation.

With all this in mind, yes, taking leave regularly when you're not really sick is abuse of the system.