I think you should run slow. Doing the workout might make sense had you run slowly Mon and yesterday. However, you did a fartlek yesterday and ran faster than necessary on Monday. You could probably get away with it since you are young and improving, but I don't think it's necessary or would serve much purpose. Fwiw, I ran the last 2 days at more than 2 min pm slower than what I raced 10k at on Sunday. Today I did 5 x 1600 at about 15 sec pm slower than 10k. Good luck on Saturday.