Respect your team’s no. People who can’t say no can’t really say yes either.

If declining is not safe, agreement stops being informative, because you can no longer tell willingness from compliance. The person who says yes to everything will eventually drop something, and you will not see it coming. Treating a no as acceptable costs you some immediate convenience and gives you a group whose answers mean something. An agreement nobody could refuse is just a slower way of being overloaded.

Make it easy to turn you down this week by asking in a way that allows the answer. If somebody says no, accept it without negotiating. Thank whoever tells you they are already at capacity.