The order sits there, sure. But my point was - who is it visible to, and who might hit that order? If it's just other clients, then depending on the number of clients, you may have a very small chance of being filled on the bid or ask compared to the chance you have trading on an exchange which everyone uses. How often do LMAX or L2 Dealer fill your limit order without having to move entirely through that price?
I have data on that, and I would say as a rule of thumb that resting limit orders on a "liquid" FX pair like EUR/USD or USD/JPY during reasonable trading hours will fill a resting limit order with full "make the spread" advantage 90%+ of the time.
Liquidity, however, is a highly volatile concept. I am a "micro scalper" and I always Buy into a falling price, so that for that moment in time, there are higher probabilities of "chasing" Sellers who are the Counterparties who can take my Bid. So it's easy to take the liquidity from "under the noses" of the Liquidity Providers, and everyone is on a "level playing field", as advertiz(s)ed.
I have actual data on this, but gaining "price advantage" in micro scalping is not always best done by "resting limit orders". You can spend a lot of time placing and moving resting limit orders. Alternatively, you can do what I do, where the Order Entry system is able to "strike" on pullbacks, thus giving a "fast retail" entry with guaranteed price improvement which does not rely upon "liquidity inside the spread".
Naive traders who hear that LMAX offers "wholesale" pricing, nearly wet their pants over the concept. But actually, although it's a cumulative advantage, and does actually happen; there's a "mix" of "reactive retail strikes" versus "proactive resting limit order" order types which will yield the overall Price Improvement.
Not to mention also that, say, compared to Dukascopy, LMAX spreads are maybe 50% - 70% narrower, and so straight "retail strikes" are already advantageous merely due to the "noisier" DOM and therefore the "momentarily narrower" spreads which are seen on LMAX.
So there are 2 or 3 cumulative advantages which retail micro scalpers can get on LMAX, and it is indeed the best thing available for retail scalpers at least in Forex which is my experience.
I've also done Market Bias analysis on the LMAX DOM elsewhere on this forum and we're discussing the degree of Market Maker "collusion" which can be discovered, even though LMAX does not show the entire Forex market, as has been noted. In short, we can discover with reasonable reliability where the Forex market is moving, before it moves, even with the limited data available on the LMAX streaming DOM.
This thread link is here, for those who are interested:
http://www.trade2win.com/boards/forex/196698-retail-day-traders-micro-scalping.html
HyperScalper