This has been entertaining; lots of good points but I think Robert is the only one that answered the OP's starting question (thread page 5). If simply pulling yourself out of a ditch/up a hill whatever using a tree/truck as a base it's always best to run the cable out as far as you can, leaving at least 5 or 6 wraps on the spool because this provides the most mechanical advantage from the winch. If you are unable to run the cable out a good distance then the alternative is to use a single pulley at the base and connect the hook end back to your vehicle or another base. The pulley is not providing mechanical advantage itself but it's allowing the winch to pull harder due to increased efficiency.
The amount of cable on the spool increases/decreases working load depending on amount of line on the spool. Your winch is rated on the first wrap of the spool but obviously you can't safely pull on that wrap, you need a safety factor. Each successive wrap decreases your pulling power but that doesn't change your mechanical advantage, it only explains why you may need to increase your mechanical advantage i.e. add more pulleys into the system to make up for lost power- which will obviously require more line. This is why most recommendations are to go at least 1.5x your vehicle weight.
However, by running the cable from the winch through the pulley and back to the winch (bumper) then you gain a mechanical advantage of 2x. The winch drum itself is considered a single pulley, so when used by itself it is a 1x force multiplier. Adding a second pulley (the one attached to the tree) and attaching the line back to the same point of the first pulley gives you a 2x multiplier.
Look at this image:
The first one with a single pulley is representative of a winch attached to a vehicle and the "load" being the tree or rock or whatever. Something to keep in mind is that if your vehicle was locked in place it would be trying to move the load (tree, rock, etc) and not the vehicle. The reason a winch works for a recovery is the the load it is pulling on has a greater resistance (weight, resistance to force, whatever) than the vehicle the winch is mounted to. Think of a towtruck, it weighs more than the vehicle it is pulling and has more resistance so the vehicle it is pulling onto the bed is what moves and not the tow truck itself. The same thing happens when you choose an anchor point for the winch cable that does not have enough resistance, so it ends up moving instead of your stuck vehicle. Pick too small a tree or a loose rock or too soft of sand/snow and you move the load instead of your vehicle.
Since the first pulley is actually the winch drum, we can easily see how a pulley attached to the load with the cable run back to the same mounting point as the winch (or first pulley) you obtain a 2x mechanical advantage.
If you then add a third pulley to the winch mounting point and then run the cable through that back to the "load" (tree, rock, land anchor, etc) the you obtain a 3x mechanical advantage.
I think this is everyone's hangup that doesn't agree, they aren't viewing the winch as the first pulley, and/or they are viewing the load as the vehicle, when it's actually the anchor point (tree, rock, etc) that is the load and we're just counting on the vehicle moving more easily than the anchor point. The force being applied to the cable and load (anchor point) is being provided by the winch motor via the first pulley which is actually the winch drum.
I hope this helps.
Sent from my SM-N950U using Tapatalk