Not really. Take the Staten Island express bus for example. Between SI and Manhattan, there is about 35 min on the Verrazano Bridge and Brooklyn-Queens Expressway, without any opportunity to get off (BQE does not even have shoulders for the most part). That's on a good day with decent traffic. In bad traffic and bad weather, that could be an hour or even more without any opportunity to get off.

EDIT: a clarification for non-New Yorkers -- people take these daily to get to work, if they work in Manhattan. The alternative is SI railroad-ferry-subway, which allows more bathroom safety but takes quite a bit longer.