I would say that typically thousands, or at least hundreds of years pass in the medium before the players enter it. I know of at least one session where the consort civilizations on the Lands each burgeoned and fell to dust before the players ever arrived.

This allows for what from a ‘game’ perspective would be considered ‘backstory’, and from a realist perspective for ‘things to happen’. Temples built, treasure hidden, etc etc. The medium is, as it seems, a living, breathing world.

This passage of time, of course, effects Derse and Prospit less than it does the rest of the medium, as their people and culture are if stagnant, at least static. The same people going in and out of the same buildings for thousands of years. It does however, give plenty of time to build up a long grudge.

In our own session it has been just over 2200 years since the creation of the medium (by a human count, not an in-medium calendar, which at this point would simply be confusing.)