Are you talking about finish sinking into the pores or ripple from the flame/quilt?
I'm talking about the finish sinking into the pores. And ripple. Which, by the way, I think have different causes.
No question that the sinking into the pores depends on the piece of wood, how it's been prepped for finishing with fillers, type of finish, etc. You no doubt saw the run of satin finished guitars a few years back where little or no filler was used, and the poly finish stuck to and sunk into the pores of the mahogany like nobody's business. Of course, that was by design, but it does make clear the importance of the various steps taken to fill the wood pores.
So the finish isn't simply sinking with time; as the wood itself continues to age, perhaps they open up a little, and/or fillers shrink a little with time, or are absorbed a bit by the wood, who knows.
On the other hand, having the flame ripple is not due to lack of fillers, or the finish sinking in; even a poly finish isn't thick enough to simply sit on top of the wood and not ripple if the wood is rippled underneath when new. What happens there, I think, is that the wood underneath is aging, and the wood that was sanded flat is simply changing a little with time, becoming rippled itself, with the various parts of the grain doing what they do in nature. The finish comes along for the ride.
And yes, my Tonare came right out of the factory with a bit o' the old nitro finish sink. I'm told that it's absolutely normal for the finishes on these babies to sink right into the wood. My guess is that for tone reasons, they go light on the filler (if they use any at all).