They have all confirmed that it was 1 all-out set.
From Steve Holman's website
"Former IRON MAN Publisher John Balik was there, often training with Arnold, and this is what he had to say about it:
Winter was Arnold’s building stage. At this point in his training he used exercises and worked them very hard—every [work] set with 100 percent effort. He worked each bodypart twice a week.
That produced great gains for Arnold over the winter, as he looked incredible on the beach when summer rolled around…
John also noted that Arnold was fond of pyramiding his poundage on the big exercises; that is, adding weight on each successive set, which reduced his reps. For example, often his reps would go 10, 8, 8, 6, 4-5, with the first two sets as lighter warmups, but adding weight on each. So the last three—8, 6, 4-5—were his key all-out mass-building work sets."
So no. Arnold never did just one work set. Drasin states the same in his vids.
