I may be wrong, but I think per regulation, brokers and market makers have to either fill internally, or post an order to an exchange within a short timeframe. (I forgot how the rules differ for marketable orders and non-marketable limit orders.) I doubt a broker as big as IB would violate this regulation systematically.
I know and this is what I told them but they don't give a f . They kept telling me my price was not at the market so they can hold it on their server and only released it when it's close to the market NBBO or whatever BS. Trust me, I know how to add liquidity on exchanges. I have been trading for over 10 years. If IB doesn't do these crap shit to screw me, I would be making at least five figures just in rebates. LOL You want to complain to FINRA? Go ahead! They don't give a f . They tell you you can only do it after 90 days and then if you complain, they will just fire you. Like I said, they don't give a f !!
You are going to find, the trading world is full of BS and most of them are directed towards us retail traders because we are at the bottom of the food chain.
I'm not sure which question in which initial post you mean; but I'm always interested in factual evidence of ways to minimize the all-in cost of order routing strategies, which is not easy to come by and hard to collect yourself short of doing a science project in and by itself. No, I don't need cheerleading, please don't waste my time; please only reply with constructive, factual input.