Say I am doing mile repeats at threshold pace and instead of taking 90 seconds rest I take 3 minutes?
u gon die
The man has a point. What you really do want to do is keep a training log and ensure that you are improving. The University of Oregon, as I recall, had two interval days per week. One was a long interval day, such as 880s to Mile Repeats, and the other day was 220s to 660s. But they had a progression for them and they timed them. But it is far better to undertrain the athlete than to overtrain them!