Negotiation is not winning every point; it is improving the total outcome.

Contesting every item makes for a longer negotiation and often a worse result. Some points cost you more to fight than they are worth, and the energy spent on them is unavailable for the things that matter. What you are optimizing is the whole outcome, including speed, relationship, and durability, not the count of arguments won. Winning points and winning the deal are different games.

Before going in, rank what you actually need in order. Concede the bottom of the list readily and visibly. That both saves time and buys credibility for the places where you do not move.