My wife and I have owned four dogs over 21 years (sometimes a couple at a time) and we've never had the insurance. Looking back over all those years, we would not have had occasion to use it once. That is, obviously, due to having good fortune with pet health (although our German shepherd/mastiff cross has been hobbled by arthritis for years, but it's not something pet insurance would cover).
That said, the newest addition to our family is a one-year-old Bernese mountain dog. At five months, she was playing hard with another dog in the neighborhood and came home limping. We took her to the vet after it didn't get better a couple of days later. She had a partially-torn cruciate ligament in her right rear leg. It required a couple of weeks of minimal on-leash activity (mostly getting out for poops and pees) and she healed up nicely.
But the cost for fully torn cruciate ligament surgery is close to $5,000. Yikes! That made us think twice about whether we should have pet insurance. A few of our neighbors swear by it. They say it's saved them considerable money.
Still, for us, four dogs over 21 years would have added up to a whole lot paid in premiums for no claims. So we're mulling it over to this day.