Something those voting for 3 or 5 trades may not be considering...
Perhaps you’re thinking you won’t need more than 3/5 trades to get the key players your team needs, but you also need to consider those times when you’re indifferent about your upcoming pick and another GM really needs it. For example, if the trade number is too limited then you may not be willing to make a simple trade that allows another GM to move up 3 spots to get his guy because that would be wasting one of your valuable trades. Of course, the very same thing may happen to you later, and you will miss your guy.
In other words, don’t forget there needs to be 2 sides to every trade.