Getting the flavour out of oak and hops

You can make a hearty cup of tea in a few minutes by pouring boiling water on a teabag and stirring it around with a teaspoon. However, if you pour the water into the cup first, gently lower in the teabag and leave it undisturbed for 5 minutes, the water will still be completely transparent and none of the tea flavour will have escaped the bag!

...this is what makes me question dry hopping. I get the feeling that leaving hops in a closed, undisturbed fermenter for a week is a more or less pointless exercise when a few minutes of squishing and stirring would have a much stronger effect (obviously while avoiding oxidising the beer!). I have only dry hopped a couple of times so haven't really experimented (though I couldn't resist squeezing the hop bag every couple of days last time), has anyone else had this thought and played about with it? Given that dry-hopping clearly does work, I would be interested to hear if anyone has a smart explanation about just letting them sit.

The reason I ask now is that I plan to add some brandy-soaked oak chips to a beer in secondary over the weekend. Back to the tea analogy - if the chips all sink to the bottom then the beer remains undisturbed for a week, surely very little oak flavour would escape the chips, and that which does would be constrained to a small layer of beer around the chips at the bottom? The posts I have read suggest sampling the beer every few days to check the level of oak, but surely a sample of beer pulled off the top will taste completely different to one pulled off the bottom?

So...does everyone secretly stir their secondaries, or can someone explain the magic that goes on in there?

It's all about diffusion. It actually works the same way with tea. Yes you're not going to get a lot of flavor out of a tea bag in 5 minutes, but if you let the tea bag sit in water for a couple days you'll get a ton of flavor out. Google "cold brewed tea" for more info. It takes time for the flavor compounds to be extracted and diffuse out through the beer.

It is true that there may be some stratification of flavors where the oak/hop flavor is more present at on layer of the beer than another at first, but if you use a wine thief to take your sample, you'll be getting a bit from both the top and bottom, so it will be a fairly accurate representation of the total character.

Thanks!
I'll give the cold brewed tea a shot when I get home - as much as I am willing to believe the science, I will feel a lot more comfortable when I have seen it in action!

As you have noted dry hopping works.

I think here is usually a little yeast action going o that moves everything around.