I don’t think any of us are saying run 8:00 mpm all the time . Run by feel and some of those days you might be running 7:30-7:45 pace. go by how your legs feel. Then two days a week pick whichever days and make them more specific — do it by feel run comfortably hard for 20-30 mins of the run with a easy warm-up and cool down. one other day throw in some strides say 10 x 20-30 secs fast but controlled. If you have to go by pace on the tempo run – then do what I said above and you be fine. I still think you can do them by feel though.