xpost DT - I don't see it as a leap. Although the table updates may suggest that: most of my pbs are over a year old. As I mentioned I had injury problems for a large part of the second half of last year and I've just not raced those distances whilst fully fit since then. After Brighton I decided to ease off and rebuild a bit, so the improvement is just steady progress from stringing together a few months of uninterrupted training.
Muddy - My paces used to be all over the place when I would just do the sessions along whichever road I was running on but I've managed to narrow then down a lot by being more selective above where I do them. Canals are good and this is my choice if I do a session from work or while visiting my parents.
One of Leamington's parks has an 800m 'cycle track' which is fairly level if a bit exposed on windy days. I've also found a very slighty undulating street circuit which is almost exactly 1mile round without crossing a road and is good for tempo intervals.
I still incorporate MP sessions into my normal gently undulating run routes, so pace varies a bit there.
DT - I had recurring injury problems last year. Although I think I did reasonable quality sessions with 1 tempo and 1 interval session of 3 miles each off about 30 - 40 mpw mileage, I think my problems came from cramming in extras like football, races and particularly doing long runs when tired. My approach now is (not to play football, ever) that if I race or similar I will drop a Q session and if I miss a run then it is missed, I don't try to cram it all into half a week. It seems to be working reasonably well, though I do have a suspicion that my right hip flexor is not quite right again today.
Marrows - Well done marrows. I just edged the 5k, but we could be sharing the 10k silver.
Well done Tommy - a big chunk of your pb. Good to meet you Wednesday.