Putting your 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 higher and that you're the most likely to extract concessions.
There are two problems with this as a tactic, though. The first is that the professional negotiator on the other side has precisely the same tactic, so it's hard to use it productively.
More important, though, is the notion that maybe, just maybe, both sides are in it for the long haul. If the relationship has to persist, if you are in this for more than this one go round, it's essential to recognize that brinksmanship costs both sides. It makes the pie smaller and it makes it more difficult for you to build something going forward.
Professional, long-term negotiations by adults should avoid the last minute out of principle. It's foolishly selfish, because it hurts both sides, thus requiring you to take even more off the table in order to benefit.
Either you negotiate to make the whole bigger, to have both sides benefit–or you negotiate to have the other side lose. Winning by punishing the other side isn't a particularly long lasting or satisfying strategy.