I buy this insurance on a per-trip basis. Some countries require it for entry (e.g. Czech Republic) but I've never had the documents examined. I haven't had to use it, but fellow travelers have, issues like emergency room trips for dehydration, sprains and broken limbs from falls. One trip we had two "return of remains" cases.
I've looked at Good Sam's plan as a full-time, low cost alternatives, but it is focused mostly on RVer needs, has too many restrictions and exclusions for the foreign travel I also do.