[turtletontine]

In an agrarian economy people are definitely much MORE attuned to the cycles of the seasons. If your town always starts planting crop X two weeks before the solstice, and the harvest festival is the week after the equinox, you’re going to keep track of these things.

[quuxplusone]

Yeah, but I took the parent comment as a non-rhetorical question. Say you were one of these "MORE attuned" people of the past: how long [literally] do you think it would take you to notice that the calendar was drifting? Like, if the calendar says the equinox should be on Monday, but in fact it's actually technically more like Tuesday, would you notice? What if it was technically on Wednesday?

If the rate of drift was like 5 days per year, then sure, people'd probably notice in a year or two — three tops, right? But how fast would the drift be? It's a question about how much people can detect small changes in daylight and how big the change actually is.

I also observe that we put up with tons of drift in our months: the new moon is hardly ever on the first of the month! And that's really easy to detect (within a day or two). So maybe people would notice a drift relative to the seasonal cycle and just not mind, the way we don't mind a drift relative to the lunar cycle.

[phainopepla2]

I think that when OP said "When would you notice" they meant you the reader in contemporary times, to draw attention to the high level of attunement you're referring to