Interesting!
Funny thing is, I've never run into the practice over many years in the business.
Mostly, if gas tubes played up,you just replaced them, & apart from regulators & the odd Thyratron from time to time, they weren't a big part of my experience.
Most equipment after the early '50s employed "hard timebases", using normal vacuum tubes.
I have certainly seen equipment with incandescent lamps inside, but they were mostly to control the feedback on Wien bridge oscillators, so as to stabilise the output level.
Here are some other "funnies":-
(1)How did the flashcubes that didn't use a battery supply work? (I do know this one, it is on line)
(2)Here is the really weird one!
Many years ago, at my work, we had made up a bunch of small Mains distribution panels which were to be fitted at the base of equipment racks.
Someone realised that 120v neon indicators (in rectangular plastic mouldings), had been fitted by mistake.
We were told to remove them, destroy them & replace them with 240v ones, so a bunch of us sat there, removing them.
Somebody suggested a good way to destroy them would be to fling them at the concrete floor.
On doing this, we discovered that on impact, the neons would briefly flash, so we had a lot of harmless fun
making this happen.
The impact definitely destroyed them, as trying again with one that had already hit the floor produced no flash.