Just limit orders isn't enough. Smart-router at IB will give price improvement over the bid-ask spread generally. Limit orders resting on an exchange can benefit from smart-routers that re-route if they see it's marketable on another venue.
I was thinking of the general case where someone who holds stocks a long time places a buy limit order on something like DIS at 130.00 GTC. It's unlikely that the stock would just touch that price, never trade 129.99 and then never revisit that price for several months. That said, several times, I have placed limit orders with pre-market execution enabled that executed pre-market, but would not have executed if I used regular trading hours. Not sure if IBKR Lite covers that execution option. It's nice to have from time to time.
