Well, tonight I finished week 4 with the 3rd run.
W4R1 was actually great! I came off it feeling like I could have gone on a tad longer (emphasis on "a tad"). R2 was a bit tougher and then R3 tonight seemed even longer.
3 x 5 mins on W5R1 right now is seeming a little intimidating. But I think I could get hooked on the kick I get when I'm done