If you get your systems right, all three go up at once. The tradeoff is a false dichotomy.
And logically, this makes sense. If you've doubled your workforce, what the hell is preventing them from going quickly and executing well at the same time? Shouldn't you expect a decent bump in efficiency, if not double then at least a moderate increase? What leads to diminishing returns when you grow?
Systems, that's what. The connections between people, between processes, and the methods of management that generate those connections.
Read up on Deming, still the best source of wisdom on the topic.
I think it all comes back down to motivation. Systems and design-level thinking is core, but there should be proper motivation.
The best posture for a specific system depends on how far you are from an optimum, and not by mindlessly claiming that "there's not free lunch" or "we can always improve".
Doesn't the fact that a change can worsen all three qualities imply that there must be a change that can also improve all three qualities?
These things are not always mutually exclusive. That's the fallacy.
Read the full phrase, not just half. I didn't say those are mutually exclusive anyway.
Personally, speed is a matter of motivation and dedication on how much you want done per unit of time.