Whereas time mattered quite a bit (like I said). As always, play what you like
How? The only difference between your group and the slowest possible group is about 8 months. That's the MAXIMUM difference. Oh, wait, 27th level, so, the difference is an extra few months. So, we're talking the max difference between the slowest possible group and your group is one year. If your campaign is seventy years long, are you really going to tell me that slowing down by about 1.5% is going to make that much of a difference?
See, I look at Dark Mistress' example of the goblins above and think that that would likely be the last session I'd sit at that table. Think about it. The goblins get trashes and the PC's fall back. Ok, fine. Couple of hours later, the goblins scout out the area and discover their losses. Ok, again, fine. They are then so well organized that they can evacuate their home in a matter of hours, taking everything of real value with them. Note, they have to be even faster because they're already gone by the time the PC's return
My first question to the DM, upon realizing that the goblins have fled would be, "Where are the tracks?" They've got, at the absolute outside, a day's head start. They're laden down with food and water (since they cannot forage if they're fleeing - and if they are foraging, they're that much easier to catch. And if they're not foraging and don't have supplies, they'll be pretty easy pickings) and their loot. A blind man should be able to follow this trail.
But, I highly suspect that if I asked this question, the tracks would magically not be findable. Because, in my experience, "a living world" is only living if it manages to make things more difficult for the PC's. The goblins fled their home? FREAKING FANTASTIC. They're now easy pickings. Certainly a heck of a lot easier than when they were in their nice, trapped, hidey hole.
However, as I said, I highly suspect that in most "living world" games, tracks would mystically vanish, wandering monsters would only attack the PC's and every opponent is more organized than the best trained modern armies.
Call it a hunch.