Here's what one type of pyramid I do: 1-2-3-5-3-2-1 minutes

1 - minute @ 98-99% of all-out sprint effort, steady 32-35mph, HR goes from 125 -> max at the end
rest, I prefer to rest by HR down to 120-125bpm (60% MHR)

2 - minutes @ 97%, steady @ 28-30mph, HR 125 -> max
rest to 120-125bpm (60% MHR)

3 - minutes @ 95% steady @ 29mph, HR 125-> max
rest to 120-125bpm (60% MHR)

5 -minutes @ 92-93%, steady @ 27mph, HR 125 -> max
rest to 120-125bpm (60% MHR)

then go back down in reverse.

The HRM isn't very useful except for determining the recovered point. Intervals by definition are all done above LT/FTP and thus, your HR will always be climbing and should hit max by the end of the interval. Aside from the physiological training, it's also mental training in knowing exactly how far and long you can hold any given speed above LT/FTP. Really helpful for races if you know you can hold 33mph for 90-seconds, which may let you get away or chase down a break.