Sealant life seems variable - I checked the Krampus last March and the sealant I put in, in 2015, was still liquid......
Re the original question, however much of a faff it is, tubeless is the solution to multiple thorn punctures. I was getting 2 or 3 per ride and just got fed up. My worst was a single thorn which stitched a neat line of four holes across a fat bike inner tube. Of course I only fixed one hole, then a mile later fixed another, then another, then another.......

Thanks everyone, really useful, some great little ideas like the tissue paper and the needle. Will give tubeless some serious thought.