Average pace hides everything that matters in an interval session. Here is what to look at instead: split spread, decay and recovery discipline.
A 6 x 400 m session compressed into one average pace tells you almost nothing. Two athletes can finish with the same average and have run completely different workouts: one steady and controlled, the other fast-then-fading.
Start with the spread. Take your fastest and slowest rep and look at the gap. Under a second across six reps at 400 m is tight, controlled work. Three seconds or more usually means the first reps were run on adrenaline rather than on the target pace.
Then look at decay: the difference between your first rep and your last. A small positive drift is normal and healthy. A steep climb in the back half means the session was pitched too fast, the recoveries were too short, or you arrived tired.
Recovery discipline is the third piece. A 1000 m in 3:15 off 90 seconds is a different session from the same 1000 m off three minutes. If your recoveries drift longer as the session goes on, the workout quietly turned into something easier than the one you planned.
Finally, compare like with like. This Tuesday's 6 x 400 against the 6 x 400 from a month ago, run on the same surface with the same recovery. That comparison is where progress actually shows up — and it is exactly what MiRitmo puts side by side automatically.