I've had tubes flash, cause damage, and not only measure perfectly fine, but go on and lead a typical, long, quiet suburban life.
Culling tubes that test poorly in their infancy is certainly wise practice. While tubes that get through boot camp obviously will lend a higher degree of confidence, let's not be lulled into a false sense of security. Tubes do hiccup and fail, and sometimes collateral damage results. The old investment adage "past performance is no indication of future results" rings true with vacuum tubes as well.
Culling tubes that test poorly in their infancy is certainly wise practice. While tubes that get through boot camp obviously will lend a higher degree of confidence, let's not be lulled into a false sense of security. Tubes do hiccup and fail, and sometimes collateral damage results. The old investment adage "past performance is no indication of future results" rings true with vacuum tubes as well.