1. After a couple of attempts where I got wildly differing results I chucked it in. Whereas the 10k method came within 2 beats a minute over 3 races, then over the months as I got fitter it increased in line with the training I put in.
2. I opted for a test over 90 mins (3 x 10k) rather than 4 mins. More scientific.
3. I'm not that much of a lightweight , but I benefit from a mix too, ideally 1LT, 1 medium recovery, 1LT (or race), 1 long recovery. We all benefit from different types of training. An LT and a long run being the foundation.