There are limits, though. Lying (or engaging in puffery) when you're negotiating a settlement is different from knowing your client is going to lie on the witness stand, yes? One you can call "negotiating tactic", the other is a violation of the cannons of ethics.
And yes, there are times it's appropriate to lie, IMO, although when you do, it's your reputation that is at stake cause I know once an adversary said something untrue, there wasn't another word they could say to me that I'd believe.... most judges feel that way about the attorneys who come before them, too. in falsus uno and all that.