here is a quote from Frank zane about Arnold.
FZ: We didn’t go to failure a lot; sometimes we’d do forced reps before a contest to push past a peak, but mostly we’d pyramid up for 6–7 sets. Surprisingly, Arnold didn’t use very heavy weights for a guy his size, but his form was great and he really knew how to isolate his muscles. He’d do curls with only 35-pound dumbbells, but because his form was so great and he’d squeeze each and every repetition, he got great results.
http://www.musclemag.com/oak-iron-frank-zane-reflects-on-his-time-with-arnold/#.U2CobGCKBjo