Renato is probably saying that guys who are able to run 13 minutes in a 5k race can time-trial in practice a 5k in 13:39 (which is 105% of 13:00) without problem. This method of training has a long history of being valuable. For 50 years, Arthur Lydiard's suggested time-trials at 7/8th effort (which is 10 seconds per mile over current 5k pace on his charts). He suggested that they should be done in the last 2-3 months, especially in the last 6 weeks, prior to a peak race because they help bring together many elements of fitness while also providing a measuring stick for determining defiencies. He pointed out often that this type of training reveals if one needs more endurance work or more speedwork. I am sure Renato adjusts training accordingly too.
If a runner gets out quickly without a struggle but later can't hold pace, they need endurance work. If a runner's legs struggle to keep up with the pack or pace early but the runner is later able to hold pace and have a nice driving finish, then it is speedwork that needs to be done. Time trials reveal weakness and strength while promoting fitness. Races can too. Tinman