*Effective* suppression ought to rely on the skill of the shooters, I think. The response to fire would indeed depend on the psychological factors of the target, including leadership, experience, et al.
Without going all Marshall on the subject, I would think you have to accommodate a range of responses: from those especially motivated who keep on going; to the green troops who dive for cover and take no action in return; to the veterans who select their cover to be able to return fire, to the war-weary who say “‘sod this”, get their heads down, and wait for the artillery.
Infantry combat was almost an ancillary part of training at the NTC (in the old days). But you still saw all kinds of responses (including total paralysis of a unit) even when the worst that could happen was that your MILES sensor would go off and you could have a sit-down.