Nothing accurate, on the second run of the second set I was manually timed at 7 seconds. So I guess it would have been low 7s assuming the timing wasn’t way off? But yes the percentages are effort not % of PB.
The 2 minutes between runs was enough to finish the run, slow down in my own time, take a leisurely walk back to the start and then catch my breath before the next run. So I was able to maintain a good pace throughout the session.
I imagine the last set was probably getting toward the top end of 7 seconds as my form was dropping off a bit on the last couple of runs.