Yes, its usually about requal although the current 4 stay for 1 free is definitely an added motivator. In fact its incredibly convenient that maximizing for this promo maximizes requal progress as well.

Still - its a point builder too in a way. If your company pays for internet and/or meals then you can take bonus points/miles per stay along with each hop as well.

Lastly - price and convenience is definitely a factor as well. There are times when the nearest Hilton property to a given travel location is either too far from the work location and/or has a significantly higher rate. Sometimes you just get tired and wuss out on changing hotels every night. I know I've wussed out a few times on a 7 or so day trip. Sure I can get 7 stays out of it but repacking up, lugging the bag, and even the issue of baking the bag in the car trunk can get old. Sometimes its just too nice a thought to just leave it there for an extra night and be able to just come back to the hotel and crash after a long day.