Russ, good points my faciliites are a 200m track indoor and 400m outdoor. My current training when I was inside would incorporate extensive drills over hurdles and runs over 60m with hurdles set every 20 to work on stride pattern and then 400 flat training. Once outside april we would focus on drills again, and regular spacing reps like 2x5H, 4H, 3H with full recovery 6-8min a rep. We also do the a 100m of hurdles spaced 20m so 5 hurdles and work on technique and rythym. I was also told by many people that in a 3-4 years training 400Hurdle time=400m+3.0-4.0 so my coach told me the number 1 priority is fast 400m and then only other thing that matters is my hurdling technique. so if the flat 400m gets faster my hurdle time will drop like u said and if my technique gets better my hurdle time will drop..Apparently once you max out your 400m you can keep training and max out your technique at about 400m flat +3.0 for a well trained athlete.