Since I have been running I have never bothered about "speedwork". The only types of run I do is typical tempo runs (8-10m @ 6:10-6:40) at marathon pace and then I do slow recovery runs (1 min. slower). My main goal is sub 3hrs marathon.
My training is very simple. I don't do and don't like hill work. The risk of injury appears to me too high (different type of running). However, I run in a hilly terrain (slowly).
Haven't explored running on the track yet or doing intervall sessions.
Over shorter distances, I can do a 5k in 17:xx. However, I am not particular interested in everything below 10k. My PB's 35:46 (10k), 1:22hr (1/2m), 2hrs(30km), 3:08hrs (Marathon).
The question is should I bother about speedwork? If so what kind of intervall should I be running? Would that be benefical for the marathon? Should I rather stretch the tempo runs a bit further?