Since Astoria needs frequent service, won't they wait 8-9 minutes for the N (if left alone)? They already are waiting 8 minutes (9 minutes for the N and Q respectively)..
Remember, trains pick up passengers for 1 minute. Yes, the N and Q run every ten minutes through most of weekdays, so by saying that trains pick up passengers for 1 minute before leaving a station, it is actually waiting 9 minutes for both trains respectively if you think about it.