IME it's not quite that simple. For one thing, you may get different rates depending on how many nights you check for. So, for example, if I have a five night stay, I'll check for the whole five, then for five single nights, then a three and a two, two and three, one and four, four and one, three, one and one, etc. Lots of different rates show up, and the trick is to optimize them. It's not unusual for me to have several different consecutive reservations for a one week stay, for example. And, yes, it can take a huge amount of time to test the different permutations.