Mentzer in his heyday. One of my old-school favourites.
I recently bought one of his books and read that when he was in that condition ('79 I think) he was using a 4 day split. (Having used 3 whole body workouts up to '76).
Throughout reading the entire book, I still kept wondering, why did he discount all the success he had using more frequent training, and preach highly infrequent workouts after he gave up competing?