This winter and spring I'm interested in racing anywhere from 800m-5k. My training so far is most compatible for the 5k. I've mostly been doing faster intervals but with pretty long jogging recovery, as in 400m jog between 800s. In my experience, I always seemed to "peak" after only a couple of short-recovery workouts. However, I've found it's easy to lose this peak unless I keep doing short-recovery workouts. An example of this happened when I would rarely run faster than 24 min for 6400m tempos. One day I did 18x400 w/30 sec recovery at around 5k pace, and for two weeks afterwards I ran almost a minute faster in my tempos. However I didn't follow-up with any other short-recovery workouts. Since then I've been averaging around 23:30 for the tempos although lately in pretty cold weather. I think I may have reaped some more permanent fitness from the 400s but also probably from raising mileage.
My question is, how often is it appropriate to do short recovery intervals if my goal races indoors are early February or say for outdoor season around April or early May? How early in the season should one try shortening the recovery between intervals? Is there a consequence of doing short recovery intervals long before a goal/peak race? Daniels training plans for the 1500m seem to have pretty long recovery between intervals throughout the season with the staple 10x400 indicator being the only exception.
Also if anyone has an idea what kind of 5k track shape is indicated by 6.4km tempos between 23:10-23:30, would love to hear what that indicates for an indoor 5k. If it helps to offer more details I ran 17:30 on the roads before the new year and I feel like I'm probably in similar shape.