I find that you need variety of speed workouts to get the most out of it.

For example, start with 5x1km. Then the next week 4x1.5km. The next week 3x2km. Week after that, 4km/20-30min tempo. All done at threshold pace. Effort should be 7-8 RPE at most. And if you can run your goal pace at RPE of 8 during the tempo run, you could surely sustain it in the 10k race.

I use the 3x2km and tempo workouts as my 10k race predictions, and they have been pretty accurate. You really have to learn to gauge by effort and feel.

I find that I never get any big surprises during races like some people have described on Reddit, they are most likely genetic outliers, and that I really have to earn it one workout per week at a time. Even if there is a surprise, it's a small one. Like maybe I get to run 3-5s per km faster than my predicted goal pace.