NY state law requires a landlord to give reasonable notice before entering. The state attorney general has previously held in Zwerin v. Geiss that reasonable notice is at minimum 24 hours and up to 1 week depending on the reason.
Often an assignment clause is necessary to protect a tenant if there is no option for sublease, if the tenant does not plan to return to the space or to help with rental costs to help tenant avoid being penalized for ending their lease prior to the end of agreement.
So first, in NYC a landlord cannot unreasonably deny a request to sublet. You must submit a written request at least 30 days in advance, and it must include things like who you'll be subletting to, why you're wanting to sublet, where you'll be during this period, etc...
NY state law requires a landlord to give reasonable notice before entering. The state attorney general has previously held in Zwerin v. Geiss that reasonable notice is at minimum 24 hours and up to 1 week depending on the reason.