I love LOW cadence work. Keep the Heart Rate to AeT, smash the cadence down to 50 RPM, go all uphills like this. hold the control, sit your rear down in the saddle and grind it out for 10-20min, like an elephant in a tutu.
THIS is why.
Sure, it looks stupid. But hey, it turned me from the guy who got out the water near the front and lost places the entire bike ride to being the guy who got out the water and kept passing people the entire bike ride.
The only question is whether you want it badly enough to put up with your mind and the comments from others?