I agree with jimscott about the importance of light. One non-CP example is my fig tree, which spends winters in my garage. I spray it with a few coats of WiltPruf to minimize water loss during dormancy and used to wrap it too. Every year it leafed out later, grew more slowly and was definitely in decline. All my smaller fig trees had already died or were traded/given away. Finally, I was giving up on the big tree too and only sprayed and didn't wrap it one winter because I didn't see the point in spending so much time on it. The following spring it sprung to life and, although it only grew a few figs, it grew a lot of new wood. I've never wrapped it again and each year it breaks dormancy right away and gets off to a great start.
I think I was messing up its clock by robbing it of all light and that it needed to sense the lengthening day going from winter into spring. Maybe it has to start some physiological processes a couple months before it can break dormancy. Without the daylength signal at that time of year, it couldn't get started until much later in the season. That's my hypothesis, anyway. It's a very testable hypothesis, by the way, if anyone has a bunch of figs and a need to do a plant physiology study.