I'm sorry but this is absolutely NOT true. It depends on the port authorities actually letting the ship stay late (and paying huge fees to do so). If the sea conditions and port space are not favorable, the ship will have to leave. However, if you are on a SHIP sponsored shore excursion, it is up to the cruise line to get you back to the ship at the next port of call, and they will pay for hotels, transportation, etc. But keep in mind there are times that the ship simply cannot wait for late excursions...it is beyond their control.
"The important thing is the rhythm. Always have rhythm in your shaking. Now a Manhattan you shake to fox-trot time, a Bronx to two-step time, a dry martini you always shake to waltz time." Nick Charle
Fantasy 1991 - Bahamas, Sea Princess 1999 - Alaska
Grand Princess 1999 - Eastern Caribbean, Rembrandt 2000 - CTN, Millenium 2001 - Western Caribbean. Sea Princess 2002 - Mexican Riveria, Summit 2002 - Pacific Repo Honolulu to Vancouver, Carnival Legend 2003 - Exotic Eastern/Southern Caribbean, Island Princess 2003 - Panama Canal, Dawn Princess 2004 - Alaska, Majesty of the Seas 2004 - Bahamas, Diamond Princess 2005 - Mexican Riveria, Enchantment of the Seas 2005 - Repo Quebec City to Fort Lauderdale, Carnival Liberty 2006 - Eastern Caribbean, Radiance of the Seas 2006 - Western Caribbean, Celebrity Century 2006/2007 - Western Caribbean, Jewel of the Seas 2007 - Transatlantic, Dawn Princess - Alaska 2008 - Carnival Fantasy 2009 - Western Caribbean, Freedom of the Seas 2009 - Eastern Caribbean - Pacific Princess Southern Caribbean 2013, Carnival Breeze 2014 - Western Caribbean.