[jakeru]

Torque specs given in most "official sources", such as say, factory service manuals, are usually given as a range.

But if you only hear one figure being stated (in a venue such as an internet discussion board) it's usually the center of the range. Surely, there's some range. There may also be fastener lubrication conditions also stated or assumed in the manual (such as, oiled fasteners, or dry-assembled fasteners.)

Often times, the torque of reusable fasteners is set such that the fastener gets close to the yield point, but before it actually yields. If you torque a fastener by hand, you can feel right when the yield starts to happen, as the torque stops increasing, but rather, reaches a plateau. This is actually a little bit more than is ideal for fastener reusability, but if you catch it quickly enough, it's pretty close to ideal.