Your other point aside, I have never seen this happen. If the bid changes the script will cancel the offer and put in a new offer for the top ordered item. Unless you are pricing using 1 hour prices, which I haven't seen anyone do, or bidding on extremely low volume items, which this script isn't designed for, it's unlikely the bid won't change for that long.
I think with low volume items it even more important to cash out immediately - whilst you're waiting for the other 14 to buy you're losing time that could be spent selling the one you already have for a profit, and if you do accumulate 15, then the price-risk is 15 times higher and you're subject to price-risk for longer since it will take you longer to sell 15 than 1. At any rate this script wasn't really designed with low volume items in mind.
I welcome and appreciate all suggestions - lots of this script's current features were suggested by users (config profiles, item removal, api-call intervals, ...) - looking forward to seeing your script if you end up making it public