I barely broke 4, admittedly when it was a bit more impressive, but always had a good kick compared to others. I didn't run high mileage - probably similar to Kerr - and would peak at 70 in season, 80-85 in cross but I never ran well over 10k on grass. I did a lot of higher volume workouts - stuff like 12x1k at tempo + a few mile effor t300s after - and trusted my conditioning to allow me to tap into more of my reserves as the end of a race.
Find parents to give birth to you that have good kicks