I have been using ACH withdrawals and have been pleased with the result. The money is transferred to my bank account and is available for use within two banking days.
I don't think there is any way to set up automatic transaction.
i use ACH all the time. i only use wires for initially funding an account
ACH is free
wire is not
i have noticed that IB ACH takes longer to clear than my other brokerage. i *suspect* they use that as a free way to get interest short term, since they are dealing with many millions being ACH'd every day. but that's speculation. their ACH does take longer than my other brokerage.
one really cool thing is the instant transfers that are available internally. what i do (to manage risk and filter profits out of my futures account) is that I periodically (at least once a week, but often once a day) internally transfer profits from my futures account into my master advisor account (I have a master advisor account that i use as a master account to trade my client's accounts). this instantly takes my profits out of my futures account. then, I can ACH from my master advisor account into a bank.
I don't think IB is sitting on your money -- ACH is a slow thing in general (I could be wrong -- but I've seen ACH between other banks and it's just as slow). It's possible the ACH corp may be sitting on your money
but my other brokerage is ALWAYS much faster than IB is for ACH's
with the same bank
so, either IB is sitting on my money (which they may do for risk management as much as anything... or interest) or the other brokerage is crediting my account BEFORE the ACH goes thru.