Putting your final demands on the table at the last minute is traditionally a successful negotiating strategy. It's at the last minute that people are focused, that the stakes are at their highest and when you're the most likely to extract concessions.
The first problem with this is that the professional negotiator on the other side has precisely the same tactic, so it's hard to use it productively.
Secondly, and more importantly, if the relationship is to persist, if you are in this for the long haul, it's essential to recognise that this brinksmanship costs both sides. It makes the pie smaller and it makes it more difficult for you to build something strong, durable, and happy going forward.