Just to offer a potentially interesting anecdotal data point (or depending on your interpretation, three data points) I have had three IN-18 tubes running pretty much 24/7 on the same three digits since 2008.

My friends and I put it together in a box as a street address sign. It contains the minimum viable circuitry; there's no logic or surge protection of any kind. It lives plugged into an AC outlet and glows 342 from my bookshelf.

It looks awesome. IN-18 tubes are one of the biggest available. If you're going to use Nixie Tubes, my $0.02 is that you should always go for the most impressive ones available because you only live once.

The location is long gone, but every passing year I am more impressed with the longevity of these tubes. If there's a takeaway from this story, it's that in my lived experience, cycling the digits to increase longevity is almost certainly more mythology than necessity.