Suggestion, look at the average volume over 50 days to get an idea of where you stand as risk for liquidity.
Your question have no safe answer and it depend also if you trade RTH only or aside of RTH. NQ or not, quit a few NQ stocks have zero vol during even a full minutes, in pre RTH, others have so small volume that this more garbage collection than trend (which is interesting to see anyway)
MarketDeepth need a constant monitoring to be of use. Otherwise better stay with monitoring bid/ask. L2 is close to "of no use" if you look at it every minutes,
you should look at it real time for a bout a minute then compute the trend/risk IB API is pretty well made to help doing that
This imply that you have it already running (unlikely you can wait a minute to finalize decision on your orders)
I don't know how to give advice on "loop" oriented coding, you typically should have "scenario" that unwind once triggered by a condition, like arrival of a tick (or any relevant event)
rogers
