Is torque relevant for steel/aluminium? Where do I find torque specs? When you are not dealing with carbon, is torque relevant?

I've never seen it mentioned on the hundreds of answers here, or the hundreds of how-tos I've read elsewhere.

Should I just tighten everything "hard enough"? If not, what's the best way to find the torque specs for old parts?
Here's a page that tells you everything you want to know about torquing bike parts. It's by the recognized leader in manifacturing bicycle specialty tools, including one of the more popular torque wrenches. (Park Tool)