Shame to hear about the illnesses guys, hope you all recover well and soon whether you decide to run or not. Definitely lots going around, clubmates entered for this one have been dropping like flies.
Seems I was 'lucky' to get sick just when I was due to start tapering, so at least I managed to get my last 20+ miler in before having to rest and it feels like I've recovered in time to still run on Sunday, will just be a bit more cautious with the pace.
Think I'll set off aiming for around 3:10-3:15 depending upon the weather, then find out the hard way whether I still have the fitness I had a month ago. Looks like it should be dry from now until the race, but forecasted for 20mph headwinds on the return half! If anyone fancies joining me at the same sort of pace then feel free - I'll be the 6ft skinny bloke fairly near the front wearing a green buff and club kit in the same shade as my avatar, black gloves, black shorts, and green+orange Asics trail shoes.
So that's two quality sessions during the week, plus a third on occasional parkrun weeks, plus a Sunday long run at a pace that is too fast for what your 5K and 10K times suggest you're ready for on easy terrain let alone on hilly trails.
If I hadn't seen the training details and this was just the 5K vs 10K question, then I would be asking whether you're doing a parkrun course that is noticeably slower than the 10K race. I would also ask you to consider whether you are really 'racing' the parkrun (I find it hard to go all out at a parkrun even if I tell myself before that I intend to). However it seems much more likely that you're running hard too much without enough easy.