Personal Background:
PRs: 19:40 / 41:24 / 1:37:11 / 3:40:40
I run about 35-45 mi/week.
The area around my house is fairly hilly and every run averages over 100ft of climbing per mile, and any speed/interval workouts I do are on these loops. This kind of training comes in very handy on hilly courses or hilly sections of flat courses where I pass large groups of people at a time, but I'm wondering if it's hurting my overall performance on flat/fast courses.
Could the lack of training on extended sections of flat terrain explain the much slower HM and marathon times, or is it more likely that I am just built to be better at the shorter distances?