I do this, too, and it helps. If you have enough time, you can also doublecheck the modules you're running and see whether they are fair. e.g. Heart of Nightfang is almost dead on its target for treasure amounts, and how the PCs use their wealth during it, etc. Counterexample: the Standing Stone is ridiculously undertreasured. I added a big treasure to a major encounter that totally lacked it. (though not to an encounter that was designed to lack treasure, heh heh)
The problem with that system is this: in one of my campaigns (as PC, not DM) another player keeps pointing to the table in the DMG and loudly declaring that we are grossly undertreasured. He always does this immediately before a major treasure distribution, and it's getting a little out of hand. Each campaign is different, and I trust the DM to keep his eye on this sort of thing. I fend off this player by pointing out that he's the one who guzzles every damn curing potion we find.