Are we talking about sagging phases or services or what?
OK, let's break it down....
Primary phases: a strap hoist or if large wire a coffin hoist.
Secondary phases: a set of rope blocks or a strap hoist.
services: a "jackstrap" , handline or rope blocks.
'course there are variations.
Fer instance, I can sag primary with a handline alone (not long runs of big wire). You simply hang your (handline) sheave at the level of the deadend bells, polymer, ect.
Split the handline, drop one end to the grunt. Take a grip out about 5 to 8 feet ( off the pole or out of the bucket). Serve the end of the handline through the bail of the grip and back to the block and secure.
Congrats! you have just made a simple block and tackle with a handline and a grip. Get the grunt to put out and you would be suprised at the pulling power.
This is just a simple example of leverage. I know many more, but I have a feeling there will be other examples from my line friends....