The landlord would be in breach of the lease if they fail to promptly fix things according to the lease.
This is rare among the high class of properties we deal with. Also, we avoid landlords with a bad reputation, as it just becomes a headache for us, too, as well as a nagging conscience. Nobody likes „slumlords“.
However, if something either isn’t fixed promptly or not to a high enough standard, and progress seems to stall, then we, the agent, should perform a more active role in dealing with the issues and applying pressure if necessary. Often, the landlords simply don’t know many technical things about properties. We have our own technical guy who did many home repairs and installations before, but normally the landlord uses their own people, for better or worse.