I rarely come by here anymore since I quit racing (I was over 60 and taking a long time to recover from a crash) and hardly ride anymore.
A common question is if one can do these without a power meter.
One can do these things without a power meter, but it is not easy. I happened to live in an area that was pretty flat and not very windy so I could use mph as a surrogate for power. The hard part is first finding your FTP mph and that hurts a lot, but finding it out with a power meter hurts just as much. In either case you give a steady effort for one hour that exhausts you and you don't feel like riding the next day. One can cheat and do a twenty minute test and adjust the FTP down.
Then bump up or bump down your FTP mph accordingly. Just remember that small increases in speed at higher speeds take a lot more power as the power required goes up with the cube of the speed.
For example if I wanted to hurt myself badly when I was in race shape for 55+ masters racing I could take my road bike out for a 40 km ride and finish it in about 63 minutes or about 24 mph. (I was not a really strong racer.) So when I did ZeCannon intervals I would do them at 25 mph. Like Waterrockets said the first two feel great. By the sixth one I was in exercise induced Tourrette's syndrome.
For me I found it best for increasing FTP to do two 90 minute rides at 85 to 90% FTP every week and one set of ZeCannon intervals. Riding at FTP didn't do much for me for training. Any other forms of sweet spot training and intervals over threshold would probably work just as well. I just happened to like ZeCannon intervals over the more old school 2x20 s or the sets of one minute intervals for raising FTP. Do what works for you.
Now the sets of one minute intervals worked really well for me for training up for 800m to 1 km attacks at the finish so I did not ignore them. IIRC I used to do them at about 33 mph.
I would also have one day every couple of weeks when I would get warmed up really well, shift to my highest gear and be at a near standstill, and then hit the pedals as hard as I could for 10 seconds and rest one minute. I would do a set of ten. If you do this make sure you are close to home when you finish. And make sure that your chain and cassette are in good shape.