When you say Bill I am not certain if upu mean Bill Bowerman og Bill Dellinger. I didi some training under both. First Boweraman coached me and some comments on Bill's training you will find here:https://www.letsrun.com/forum/flat_read.php?board=1&id=435103&thread=432770
My third year in Eugene Dellinger coached me. Last year I pcked up a used copy of Bill D's book which I had never seen before. The training Bill describes in the book is from his best period as a coach whith Salazar and a bunch of guys runining fast times. When I was in Eugene Pre was Bill's star runner so this was some years before. The principles in the book are the same we ran under but they are developed further by time he wrote the book.
The times run on the easy runs varied from runner to runner. I belive most of us probably ran between 6.30 and 6.00 on most of those depending on how we felt. I never timed those and it never said to run at a given pace on the schedules.
With Bill D the hard days were so demanding that you had to adjust your easy running to make sure you got your rest.