Let’s be clear: in a negotiation, greatest value comes from collaborative, proactive and trusty relationships between the parties.

Anyway, if we did not care at all about how final value will be split amongst negotiating partners, great part of that value would likely flow in the pocket of the party who has higher game control.
For centuries, wars have been nothing else than the way counterparties defined who should grab the greater part of value. A battle always lasted less than the following negotiation. Wars never decided anything but who would have led the following negotiation.

Nobody says conflictual attitude is the way. What matters is to be aware, from the very beginning of a negotiation, of which part of value we are interested in and how we will guarantee a fair value allocation.
Florence, Strozzi palace, American Art 1961-2001