The first two cruises we did not buy insurance. Came here and read how imporant it is to have. Therefore we have purchased Cruise Ins for all of our other cruises. Fortunately we have never had to use it.
Always, and always within the time period so that pre-existing conditions are covered for us and our immediate family (even if they are not traveling with us). My parents had to use it once and it was well worth the relatively small amount of $.
I have mostly bought the RCI "cruise care" but recently found out that I may not need it. My home insurance has a travel insurance part that covers up to 4 weeks (including full refund if I can't go due to illness etc.). Longer than that and I have to add a travel insurance, but that has not been a problem so far.
I have been looking at separate travel insurance to see if I will have a better coverage than with my home insurance, but can not find any big difference.
So, to answer your question John - I'm always covered by travel insurance, just no need to buy a separate one (I think...:whistle.
I learned to buy insurance the hard way on second cruise fell and broke ankle in Cayman Islands and had to fly home did not have insurance was very expensive out of my pocket. We always buy it now. We have had to cancel several cruises and was glad we had it. Paw's good camera was stolen on one cruise. Like the piece of mind having insurance.