I can only speak to what I have been given for training, but rarely are my intervals at maximum. Most of them are in the 60-80 percent range and are longer duration. Say a minimum of 15 minutes.

Higher intensity intervals are never over 90 percent and most of them have been even shorter.

Longest interval workout I have been given is 3 20 minute intervals at 80 percent with a 5 minute rest in between.