Part of the problem here is in the labels being applied to the workouts.
A lot of people use the term speedwork or speed workouts for almost any interval workout with reps of 400 or less. That's wrong and confusing, has been for a long time, but it's not going away.
What you're talking about is more accurately described as speed development. That usually means reps of less than 200, often way less, with longer full recoveries of multiple minutes.
You're no doubt correct that completely neglecting any of that for an extended period of time did limit your 5k and 10k performances, especially 5k.
You're also probably correct that the OP is having, or is at least susceptible to, the same limitations. Her times and workouts don't exactly match up.
Another key factor in all this is age -- both chronological age and running/training age. A lot of the literature and science says that speed development has a finite window during which it can substantially be improved. It would make a difference whether OP is high school, college, or post collegiate.
Yes, this is a somewhat separate issue from the repeat miles workout and what it indicates. But it's very relevant to what the OP is capable of.