Do you know your threshold pace?
I'm going by Jack Daniels pace charts at the moment, which use a lower value than the previous training plan I was focussing on. But that varies, the mile training plan pace is quite a bit faster than the 5k-15k. (partly cuz my mile is faster than my 5k) And he increases it incrementally for longer distance. I also adjust to what seems reasonable. So the short answer is, on any given day, I do.
ehh? As I understand it, Threshold/T/Tempo is just below the point at which blood lactate continues to increase. I guess it could vary a little on any given day, but should be fairly constant day to day. Generally, 85% VO2 Max plus/minus, or 90% max HR plus/minus.
the values referenced above are based on your current race times.
yes. but also on the assumption that the time you pick is for a race that you were prepared for (well rested, etc). I don't know if your actual threshold changes when your tired. But seems like trying to run a Q workout on tired legs would be counter-productive and elevating the risk for injury.
true - but it can also help train your legs to perform when they are tired, or to build on the residual stress to strengthen them. I'm a far cry from a so-called elite runner, but if they backed off every time they felt tired or sore, they'd hardly be getting any training done.
Its a judgement call, which is why i pulled out the day before when it was clear I wasn't hitting the times on the least stressful part of the wokrout, the slower, longer intervals. When I hit those much more easily the next day, that encouraged me to go finish it out.