It's definitely on a case-by-case basis.

Set your ring of putty, thread everything together, and tighten until you get decent putty squeezeout and the drain is properly seated on the sink...not standing proud.

But it's definitely a "Goldilocks" type of thing. Not too loose. Not too tight. Just right.

Thanks. Would you typically use a wrench on the last couple of turns? It's the last couple I'm worried about ;)

I'm not living in the house, so I'm figuring on a bucket in the vanity, and asking the people to keep an eye on it the first couple of weeks.

A good way to gauge things it to drop the drain into place with no putty. See how the drain flange sits in the sink, you'll be looking for that same picture when you are done.

I usually make a snake from plumbers putty and set that in place. Drop the drain into place. Compress the putty by pushing the drain down with my fingers.

Then I thread the nut on the bottom. Hnad-tighten first, then moving in with a wrench.

When you hit resistance, then you need to pay attention.

Look at the drain up top. It should essentially be as it was when you dry fit it.

If there is a washer or gasket on the underside, make sure it's in full contact or evenly compressed. With the drain looking good on top and the nut compressing the gasket on the bottom, you're in good shape.

If you go hand tight plus another half turn or so, you'll be in good shape. Watch for leaks and snug it more if needed.

Awesome. Thanks very much. I knew you'd have some formula. That's a good way of looking at it. (The dry fit idea.)