Reminds me of why torture as a means of information gathering is ridiculous.
I will absolutely tell you what I think you want to hear when you start stabbing me, whether its the truth or I ever knew it at all.
But I also hate you for torturing me, so If I do happen to know the thing then I also know enough about the thing to alter the answer to something false but plausible for a moment of relief while you act on it, because we all know if you're torturing me, you have no intention of letting me out alive.
This is why the lets be pals/wine and dine approach is more effective.
"Thanks for finally providing some info. We are going to go corroborate it. If you lied, or if we can't find convincing evidence your info was right, we will take this conversation up with your wife/kid/family"
This is why I liked the how Torture skill in Burning Wheel does just this: you decide what the victim says. It's not true, it's just what they admit to.
They do still have the option to remain silent, though, as per the spell text. It doesn't compel an answer, it only compels any spoken word to be the truth as you know it.
Pain can be efficient or counterproductive depending on the individual. The threat or pain is usually more efficient than the pain itself.
Your "let's be pal" approach is not far from the KUBARK's recommendations, but it is not incompatible with coercitive methods: On the contrary several of these consist in putting the interrogatee in a state where the interrogator is perceived as a reassuring presence.