Tube testers

I had a quality tube tester, really didn’t use it much. I bought new tubes from well known suppliers that have already done that work. Used tube testing is a crap shoot. An old tube can measure perfect and be at the end of it’s life the next day. Unless you are in the business of selling tubes, skip it and just buy good tubes from good suppliers.

"...was wondering if others had the same experiences as @russ69 with sudden tube failures even when they tested well..."

Well, I’ve had brand new rigorously tested tubes that were bad right off the start. Mostly noisy preamp tubes in hi gain circuits. Also tubes can fail an infant death after just a few hours of use. Or they can degrade slowly and at different rates. In my experience one tube will sonically fail without warning and will need to be replaced, testing a failed tube is fruitless. I buy new production tubes that have been burned in and tested, no need to do that twice, then I run them until they fail, sometimes spectacularly!
Culling tubes that have not had good screening or used tubes is not always successful judging by the number of unhappy customers with some tube retailers. 

"...I can't imagine having to replace one tube at a time when something is not sounding right to find the bad one..."

That is exactly what you will do when testing tubes. Listening is often better than measuring.