I think it's common sense to say that the longer away from a crime it gets prosecuted, the less deterrent effect there is.
I admired Truman, among many other things, because he integrated the Army. I admired JFK because the very first civil rights legislation was passed at his insistence. JFK showed what you could do, though he was a deeply flawed person, as we all now know.
Companies do not commit crimes; only their agents do. And while a company might get the benefit of some such crimes, prosecuting the company would inevitably punish, directly or indirectly, the many employees and shareholders who were totally innocent.
In my experience, most federal prosecutors, at every level, are seeking to make a name for themselves, and the best way to do that is by prosecuting some high-level person. While companies that are indicted almost always settle, individual defendants whose careers are at stake will often go to trial.
An application of judicial power that does not rest on facts is worse than mindless, it is inherently dangerous. If its deployment does not rest on facts - cold, hard, solid facts, established either by admissions or by trials - it serves no lawful or moral purpose and is simply an engine of oppression.
Why should the court impose a judgment in a case in which the SEC alleges a serious securities fraud, but the defendant neither admits nor denies wrongdoing?