Sure, in theory any tube can degrade the sound as it gets old and tired or starts to fail due to some kind of manufacturing defect.

The voltage regulator tubes should last a very long time, like the lifetime of your amp.

Rectifier tubes are all over the map. With current production Chinese rectifiers the lifetime can be measured in months, sometimes even weeks. Quality NOS rectifiers from the "golden age of tube tech" ought to last several years, at least. Often they last a decade or more.

But there are no guarantees, for good or bad.  Any tube is subject to degradation or failure at any time and even the cheapest Chinese tubes can give years of quality service. The only tube I had fail in my Decware amps was a high dollar Mullard GZ34 rectifier than should have outlived me. The best (only?) way to know for sure is to swap tubes out with new/good tubes occasionally  and listen for differences. If you don't hear any problems than continue with your current tubes. If you do, time for a change. And if you don't have at least one spare set of tubes you should get one, right now.

I don't think I have had any VRs fail, but I tend to roll them, so have not run any as long as I have my amps that use them by any means. I have had a few rectifiers fail over time, but surprisingly few considering how much I use my amps. That said I am pretty sure I recall some threads here where the VR was a culprit for problems but can't recall where. Lon may remember, or it may have been him.

I am with CAJames, I would have spares on hand. Even VRs, perhaps usually the longest lasting, many are "NOS" (the nicer ones to me) with who knows how much real wear on them or what they have experienced in transport or whatever.

I may be a little particular in that after many years of tube tuning in Toriis, I get pretty attached to my sound with certain tube combinations. But this came from trying lots of them over time, so I have abundant backups and I can make a number of sound variations I love, feeling in sync with my listening needs, but shaking up my experience enough to make it new. I learn this way.

So I like having backups not just to be able to listen, but also to shift my listening world, really liking to experience it a little differently on occasion. And my "backups" are different, giving whatever combination I like at a time more flexibility for fine tuning. So for me, they make my music more compelling. But I listen a lot, creative medicine to me.

I have had one VR tube fail on me, but I think it had been old and used a long time before I got it as a matched pair. I just retired its partner too, as I need pairs of them (they were 0CW JAN tubes). I think another here has had a failure as well. They can last a long time. Like Will I have been building favored tube complements over time, and VR tubes are often part of the "anchor" tubes for the complements. I've run across a few "tired ones"--I just replaced a pair of RCA 0D3 that I really liked with a newly acquired pair (these had silver ink which I think means they were "younger" than the previous pair with red ink on the base)--in comparison to the new pair the older pair with red ink on the base seemed less dynamic and a bit "smoother" in a tonal way.

It amazes me how voltage regulation tubes, even different brands and types of the same basic tube, make such a distinct difference in the tube complements of these components. I think with as simple circuitry and as undeniably transparent as these components are. . . nearly everything in the system "matters." We're really blessed to have this level of audio excellence in our lives, even though at times it can be frustrating and maddening when averse parts or combinations arise.