Generally speaking - it is better to give than to receive.
That is unless you're selling something, in which case only suckers give without receiving. Reciprocity is the name of the game when it comes to negotiating with a prospective customer, partner, etc.
A very simple example
- Prospect asks for a discount on product XYZ.
- Rookie says "OK".
- Killer says "Sure - I can give you that discount on an annual agreement executed this week".
This is a difficult discipline to build because most salespeople are natural pleasers - who doesn't want to make the customer happy by giving them what they want?!? It takes a lot of confidence to tell a prospect that is ready to buy "no", in part because it is always sooo tempting to just get the deal done.
The reality is that a lack of this discipline can get very expensive, very fast. A skilled negotiator on the other side of the table is going to keep asking until the Rookie says "no" and tear the rep to shreds in the process. (I've been on the giving and receiving end of said shredding process!)
Putting a condition on most "yes" answers is a great way to diffuse this problem.