Exactly. But we're actually talking about 3 things: time, quality, and scope. Pick any two.
I had the pleasure of working with a company that preferred time and quality, and were willing to negotiate scope. It worked really well, because, from the outside, it looked like we were releasing on a regular basis (so it looked alive), at high quality, and on the inside, we knew we'd ship the more difficult parts of the project eventually, but without the stress that goes with trading off time or quality.
I had the pleasure of working with a company that preferred time and quality, and were willing to negotiate scope. It worked really well, because, from the outside, it looked like we were releasing on a regular basis (so it looked alive), at high quality, and on the inside, we knew we'd ship the more difficult parts of the project eventually, but without the stress that goes with trading off time or quality.