This. I hate hearing people whine about "still a junior engineer at 25" or boasting that they "reached senior engineer at 24 after 3 years" or whatever nonsense. It's apples and oranges between companies.
It's about the value you are able to bring, not howmany days you worked.
I'm less clear on if it's value. There's "direct value", like, I literally helped make $X, or so. And then there's "what my employer wants done", which might very well be worthless. For the latter, I could argue that I am valuable to them, from their perspective, as I am doing what they desire … even if ultimately it is not worth something.
That is, I've plugged away at many valueless projects, things that the company wanted done, but ultimately won't bring value. Nonetheless, I can bring my experience to bear on the problem and move a mountain or two.
The times I have brought value have usually been quick and unexpectedly. Like, just by being aware of what's running & catching a $20k/month mistake. Or understanding how something is done, to unstick / enable someone else. But it is often not part of my goals, what I am doing day-to-day, or something I get to claim/matters in performance reviews.
And sometimes, you don't get to know what your value is. I remember at one company we had this really onerous customer: completely custom thing was built for them, it was always lots of back and forth, weird corner cases, just lots and lots of custom stuff. We thought we were mostly bending over backwards for someone for little gain. Turned out they paid quite well, but for the longest time, we had no idea: finance didn't share that information with us. And this is true of most companies I've worked for: the financial details are completely opaque, unshared, and I couldn't tell you if I'm bringing value or not, ultimately.
There's a lot of people with the same 1 year of experience repeated several times, who then call themselves 'Senior' based only on number of years.