I think it depends upon the type of tulip, and how they've been grown. I used to do the pin-prick thing, and sometimes it worked, and sometimes it didn't. Just as some last longer than others, depending on how tired they are when bought. Sometimes the fresher they are, straight from the garden for instance, the more likely they are to remain upright.In fact, I prefer mine to flop and am disappointed if some stay resolutely upright.
They also continue to elongate, so it might have something to do with the type of vase they are in, as they continue to grow.
As I love tulips, am happy for them to do their thing. Upright or floppy, they are a delight.