Voodoo76

I would keep doing what you are with the medium length intervals. However if you find you arn't generating sufficient speed increase the rest interval (I would do something like 1 to 2 min). It's great to have a long sprint as an option and what you are doing here will help develop that. I wouldn't do consecutive days training this way, you want to be rested an able to push your max up. If you are cycling your training then as you taper reduce the number of intervals (the intensity will naturally come up as you rest more).

Very important I would add Jumps to the start of 2 to 3 workouts a week. From 5 to 10mph in a 53X17 accelerate as hard as you can to 20 to 25 mph (you don't need to spin out), sit down and rest. Do 4 to 6 at the end of your warmup on any hard training day. These are fun to do with other riders.

recneps, you don't necessarly train your sprint the way you would race it.