That we all believe the first of January to be the first of January, is testament to the power of mankind.
Our lives aren't shortened when we adjust clocks, say for summertime, (or is that an arcane British tendency- BST?) we simply adjust our concept of it. We could all adopt a calender that runs backwards if we wished. Confusing you may think but no more than assuming that Monday has to follow Sunday for example.
Similarly when the Gregorian calender was adopted in England, 200 odd years before Russia, their was the inevitable outcry that 10 days worth of living were "stolen"... but life still happened, everyone rose for breakfast the following morning.
This shift in meaning happens elsewhere, remember when the EU switched to Euros from National currencies, a loaf of bread was worth the same amount it just had a different cost on the price tag. (Perhaps a bad analogy, I know myself that lots of businesses used the opportunity to hoik (raise) their prices, but the principle is right I think)
Thinking about it the only calender items you couldn't shift in such a way would be things like solstices and equinox? , and it's been a very long time since people used these as significant calender events, (I'm thinking of the pre-christian druids, Pagans, Stonehenge etc?) Prescribed by the rotation of the planet, it's seasons and not it's inhabitants. 1 revolution every 24:04 or so hours. 365 1/4 day a year. (To explain, the odd mins each day are massed into a quarter day, that every four years is celebrated as the 29th of Feb or Leap year)
Man is the only creature to wear a watch!