Apartment rental question

I’m just about to sign a lease for an apartment in the upper Kirby area. This is my first time leasing an apartment in the US so I read the lease pretty carefully.

There is a clause in the agreement saying that guests are prohibited from staying more than four days at a time. My family lives in Australia, so will obviously be looking to stay a little longer than four days when they visit (assuming of course that we’re ever allowed to travel again… the joys of 2020)

Is this a normal restriction to find in a lease agreement? And if so, how strictly are rules such as this generally enforced?