I will not touch theory either. I'm not entirely sure why this crank fixing subject became controversial, but it is. Maybe it's just as well it's being supplanted by pinch bolts and splines.

I will say that as a practical matter, it is a very good idea to use a torque wrench to fix cranks. Most of the time they come undone, it's because they weren't on sufficiently tight to begin with. If you're not wrenching on this stuff every day, 'feel' isn't necessarily good enough.