The bunch of us that my coach trains religiously hit the hills. Not to climb. We use our training gears, in my case is an 88" Roll down and attck the last part of the slope. Then fly along the flat at speeds exceding that we race at. Its called over speeding.
What it does is simple. It makes your legs go way faster than they will in a race. Your training the nurological side of spin. In return you get a super smooth pedal stroke at lower cadences and your legs have the ability to keep accelerating.
Some people dont see how it works....but my coach has WC stripes