I can totally understand your point. So.... maybe look at the tree. If it's looking like it's got a natural lean or heavy side AND you can make THAT the falling side, maybe it's worth a try. If it's leaning the wrong way and you're trying to push against it.... then go with your gut feel.
One of my thoughts is if I'm standing at the bottom of the tree with no 'guarantee' that it's going to fall in a given direction, I'd rather have some horsepower behind me helping to assist/force it into that direction.
Remember, most trees are standing vertical (note, I did not say plumb) Point being, most of their weight is vertical so the power to assist/adjust/force it to a direction isn't as high as the same tree that has a natural lean OR, might be falling over and hung up in another tree at which point you pretty well know which direction it has to fall so you just figure out how to safely do it.
(did I just use the word safely and pushing trees over in the same sentence? Geez.... someone bit** slap me)