It’s annoying when someone keeps giving me their speech, or venting, when I already said ‘yes’. Are they worried I’m saying ‘yes’ for the wrong reason? It’s hard for me to stay polite at times like that.
According to Robert J. Ringer
A dealmaker, or negotiator, is really just a good salesman, so he should try to heed all the prudent rules that apply to good salesmanship. And every good salesman knows the danger of kicking an open door; i.e., continuing to sell after the prospect has already agreed to buy. The smart salesman or negotiator knows when to stop selling and negotiating, and develops the self-discipline to act accordingly. The more you talk, the more you increase your chances of saying something that may open a can of worms and kill a deal at the eleventh hour. In particular, never get carried away and introduce into a deal one or more after-the-fact bonuses in the form of new ideas, people, or thoughts. This can prove to be a costly mistake, one that often results in reopening negotiations — or, worse, killing a deal that was already in the bag.