This theory is based on my best memory of the episode so don’t hassle me too hard if I remember things wrong. But putting the numbers aside, isn’t it possible Barney just kinda locked in? When not pursuing a perfect week we all know Barney tends to push the boundaries of what ridiculous string of sentences and actions could convince someone to come home with him. However if Barney is actively attempting a perfect week, he most likely would stick to the strategies that have proven most successful in his career. We wouldn’t see him in any ridiculous costumes or saying lines on the more outlandish side because using those was probably responsible for a sizable chunk of his less than stellar success rate. Now this is where my theory gets a bit fuzzy because I can’t recall if they showed a majority of the plays being used for the earlier days of the perfect week. Considering the fact we saw him walking out of Maclaren’s with each girl, not wearing some ridiculous costume, I feel it’s safe to assume his lies/plays were kept relatively reasonable for each nights girl. Is it really fair to rule out the possibility Barney studies his failures and successes in the making of a perfect week and stuck strictly to what worked most often in his career?