I think people are confused about tipping in NY restaurants.

The tipping system in restaurants is the customers' guarantee of adequate, polite, professional and respectful service. It is not a "merit system".  You do not reward the waitstaff for great food or punish them for forgetting to bring you water or bread. Those purposes are easily handled by a simple compliment or polite request. 

Tipping is not "individual". TIps are mostly pooled and shared among waitstaff. It is not personal and should not be treated as such. Tip your 18-25% consistently.  There is no discretion required.  You do not need to "review" the service and decide on a tip.  It should not be uncomfortable or difficult.

Only on extremely rare occasions should one punish or reward with a tip. For the most part, it is routine.  It should be considered as part of the cost of the meal. 

But those rare occasions are precisely why the tipping system is good. It makes abominable experiences virtually non-existent in NY. The waitstaff has the power to ruin your meal.   Tipping is your power. You don't have to use it.  It just has to be there.

A zero tip from a local sends a two part message; something went very very wrong and I won't be back.

A large tip says, "Happy Holidays" or "Sorry my friend puked on the table".