One breath for all three reps. From beginning of first rep to lockout of third rep I average 2.65 seconds.
If I took up to 3.5 seconds, I could probably be doing speed work with 250+. That is more weight than Louie Simmons uses for his speed work, and he benched 570 a few months ago.
Before I really understood the purpose of speed day, I worked up into the 260-270 range for 8 triples. I could do all the reps, and actually paused the last rep, but speed was terrible, and I was not getting the benefit of speed day. I was doing almost the equivalent of 2 heavy days per week.
Keep your reps in the 2.5 to 3.0 second range, and do them all in one breath.
B.