The best exit interview I ever gave was with the incoming security manager. I laid out all the gory details for him, told him what he was going to find and where to look for it. It was a delightful interview. The organization didn't really want to deal with the reality, but it was a pretty big business risk nonetheless.

Sadly, for them, he promptly quit a week later. I don't know for sure if it was my exit interview that convinced him.

Other than that, I generally follow the advice in the article. Keep it kinda bland. But that's mostly because I'm old and very experienced, and by the time I leave it's because management has clearly indicated they're not going to change things. I've already told them the problems, because I'm not afraid of retaliation. So everyone is on the same page, and if I don't like that page, I step away.

It helps to have a strong network of good former coworkers so I can just find another gig if this one doesn't suit me.