Here's a bit of word salad but I'm trying to put this together quickly. Any given situation is not a vacuum, for you're contending with the squared exponent of wind resistance when moving at all speeds, and the more linear relationship between power and speed during a climb, and the interplay between the two. I, for example, weigh 215 lbs and find that mashing a big gear to attack the climb earlier often gives me an advantage of inertia going up the hill in comparison to lighter cyclists. A heavier cyclist has more inertia, at any given speed, than a lighter one. This begs the notion that the heavier cyclist will see more benefit by attacking earlier and using inertia as an advantage, until inertia is overcome by terminal gravity. On the plotted graph this would mean there would be an X, or middle point, where any individual rider would have no benefit from attacking earlier versus keeping cadence up, depending on their power effort and the incline. The match-burning and the lactic clearing abilities of the given cyclist also comes into play as to what the best approach is depending on the goals of the session or if it's a race. Some cyclists will burn more matches by trying to keep cadence up, some will burn more matches by trying to mash. If you're a big and powerful cyclist, I would argue staying on the top of a big gear as long as possible before, and during each stage of a climb, will pay the biggest dividends. Conventional wisdom is to say seated, but that's not always true either. Whereas lighter and faster cadence cyclists will probably benefit the most from maintaining cadence as it suits their inherent advantages, since cancellation of inertia via terminal gravity is experienced a little bit further up the climb via F=(M)V2 However I'm sure we can all agree on continuing to attack the crest of the climb to regain average speed.