It's been a while since I did any running above 7:50/mile pace. Although with a 10k next Sunday I decided to add 1 mile at 10k effort into my 8.5 mile run this morning. I haven't improved my aerobic pace by any big margin since I started BT, but I was struck by the difference in feel of the mile I did. The lactic acid build up was very slow and my breathing was under control the whole time - no way did it feel like I was hitting 90% MHR the whole time. 6:41/mile and I'm quite happy with that. I'm still feeling sluggish, but another session this week and one early next week and I should be in better shape.
Given this, I'm considering cutting my BT short by two weeks. This would give me 12 weeks to complete my 10k training cycle, which I reckon would be more beneficial. I seem to have a reasonable base already from sports over the years, so after the 10k race I might just capitulate and start the mesocycle.