[AMRadio] Tube checker gas check vs real world

[CL in NC]

I have an old Hickok tube tester that can run a gas check.  What is the real world experience with tubes that pass the gas (ha ha) test on the tube checker, vs being gassy when in a circuit?
While the information about the gas test says it is aimed at amplifier tubes, guessing they mean primarily, audio amps.  What are your thoughts on testing 572B's for gas?  If they pass the test in a checker that uses comparatively low voltages, guessing that does not mean when I put 2100 on the plate of a 572B it won't flash over.

Charlie, W4MEC in NC