So I will do my best to explain it, one of the hard problems here is this is just kinda second nature for me. So I may not do a good enough job of explaining it.
But ok so for me, I basically am always resting my thumb (I am right handed if that helps visualize) on the bottom-ish part of my trackpad. So so when I am moving my mouse I have 2 fingers on it. My thumb is just sitting there and my index is moving around.
My thumb is basically my clicking button. It doesn't have to be, but for me it is. It also doesn't have to be at the bottom, I can click anywhere which is nice when I am quickly going from my keyboard to my trackpad and need to click something.
So because I click with my thumb and move with my other finger(s). I can click to drag, select, whatever it is that I am doing with my thumb. And them move with my other finger. With my thumb staying down, I am free to pickup and move my finger as many times as I need. I can pickup my finger for as long as I need to and it will stay selected for as long as my thumb is still there "pressed".
With acceleration that Mac uses, with just a few quick swipes I can easily move a window between 3 monitors.
Since the trackpad is also not physically moving when I "click", it is just pressure sensitive. It also isn't a strain to keep my thumb down.
Oh I get using your thumb to click/hold like it's a button. I was questioning the three-finger-drag but the other comment answered it, the gesture is "sticky" so you can reposition quickly when you hit the edge.
But ok so for me, I basically am always resting my thumb (I am right handed if that helps visualize) on the bottom-ish part of my trackpad. So so when I am moving my mouse I have 2 fingers on it. My thumb is just sitting there and my index is moving around.
My thumb is basically my clicking button. It doesn't have to be, but for me it is. It also doesn't have to be at the bottom, I can click anywhere which is nice when I am quickly going from my keyboard to my trackpad and need to click something.
So because I click with my thumb and move with my other finger(s). I can click to drag, select, whatever it is that I am doing with my thumb. And them move with my other finger. With my thumb staying down, I am free to pickup and move my finger as many times as I need. I can pickup my finger for as long as I need to and it will stay selected for as long as my thumb is still there "pressed".
With acceleration that Mac uses, with just a few quick swipes I can easily move a window between 3 monitors.
Since the trackpad is also not physically moving when I "click", it is just pressure sensitive. It also isn't a strain to keep my thumb down.