A landlord has the right to enter the apartment when there are things broken on an emergency basis and can come into the apartment with 24 hour written notice to "check on things" on an as needed or reasonable basis. He cannot just use this right to violate your rights. You have the right to "quiet enjoyment".
The problem here is do you want to go through a legal process to fight with the landlord? It doesn't look like he has done anything to violate your rights, clearly. This is "on the line". Has he crossed the line? Hard to prove. There is no exact law on how many times is beyond reasonable.
Your best options may be to find another place, or put him on notice that you believe that he is violating your rights to "quiet enjoyment". I would ask him to put in writing why he needs to come in so often. Is there something wrong with the property?
You can write him a letter that you will pay for an fix minor things, and will let him know what those are.
Other than that, you can put up with it or you may have to find a new place.
This is general legal advice intended for informational purposes only and does not create and attorney/client relationship. If you wish further advice, please contact an attorney of your own choosing or you may contact me for further advice and make other arrangements including retaining my services.