I have kidney failure and a strict 1000mg. Most low sodium diets allow 2000mg. I need my food cooked without salt. Basically i need whole foods. No sauces, no salad dressing except vinegar and oil, unsalted butter. A slice of bread or a roll may have 100-300mg of sodium! Baked potato rather than mashed potato (1/2 cup of mashed potato is about 350 mg).Unless your specific requirements are defined you can easily exceed your sodium limit.
Once you know your own requirements its a matter of getting the matre'd or food manager on your side. Its your life - be vigilant!
The good news, so far Viking, NCL, Celebrity and Royal Caribbean have all step up and helped me meet my requirements.