With that particular tackle it's unlikely you can actually load it by hand to beyond your limits... if you don't put it on a winch I don't think you can ever get too much load on it.
So I think you can play with your adjustment to your heart's content. As Steve says above, observe the effects and figure out what actually works.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"