Take today for ex., Google and MyZmanim (and probably e/o else) have sunset in NYC (Zips that I checked) at 7:41; Chabad.org? 7:43!
Unfortunately, the fact is there are many who for whatever reason (intentionally or not) do take it to the last minute sometimes (I confess), and this is a bit unsettling. I mean we're not talking about davening mincha here...