Sometimes fast thinking is fast. If you have mental models that the other doesnt, and those mental models are good in the limit of the context you’re in, it’s faster.
Of course if you both have the same mental models, or the models don’t work in the limit of your context, then more time lets you think deeper. Take chess. Two players in a 1min bullet game (mental models very applicable) vs two players in a 20min grandmaster battle (better to take time and think deeper)
Speaking before you think makes you look dumb, but it doesn't make you dumb. You see the difference? You might have met many such people who were smart, but that you identified as dumb since they weren't afraid of appearing dumb.
Skilled liars are usually quick though because they're not considering if something is correct or not, they just need to figure out what kind of thing to say to make you agree with them.
A better sign of intelligence is knowing when thinking deeply is in place. And most often it's not. Most often it's more cumbersome to think for a long time than making the occasional mistake.
People that think long & hard about everything don't have their priorities right.
If you're doing a research or fun project, where failure has no consequence? Then yeah, mess around, move stuff, go fast, break things. Worse is better.
There are so many situations where there are, consequences, though. Either because failure is pretty dang bad, or (perhaps more commonly for our industry) a mistake will increase our tech debt. Our failure to spend a few extra hours thinking it through in the short term might lead to hundreds of hours of tech debt or (in the extreme case) our entire project/company to fail in the long run.
The previous comment seems to suggest that a sign of intellice is taking time to think, in general. I'm saying a sign of intelligence is knowing when thinking longer is worth it. Some people take their time every single time, and I wouldn't say that this indicates that they're smart...
Q: What's the difference between a novice and an expert?
A: The novice thinks twice before doing something stupid.
If you and I are working on Project Blahblahblah with a team of 20, sure, we're iterating that. But the crazy bad, hacky, barely-works spaghetti code I crammed in there for feature ABC? It might be a long time until we get to iterate on that particular ball of tech debt.
I think maybe that's why I'm burning out on this industry. It's ship, ship, ship, new, new, new and never a chance to iterate for quality.
The goal is to avoid blockers, not enumerate them uselessly.
Can it be done? Yea? Sure ok then let’s figure it out. The million ways it can’t aren’t relevant.
CAN IT BE DONE? OH YEAH!
How hard to push back depends on the nature of discussion. Being too pessimistic in a research phase is not useful. But if it’s a contract worth half a year or more, spending few days evaluating assumptions is wise.
Remember that fast thinking is not actually fast, but shallow and/or optimistic.