This is a post that I've been meaning to write for a long time and I probably won't do justice to. So look forward to me rewriting it in the future :). But a valuable lesson that has (literally) been beaten into my brain since I started playing football in 3rd grade is always go full speed.
Some of the more obvious safety beneftis of this is when you slow down or hesistate in football, you tend to be more prone to twisting your ankle or falling the wrong way and hurting your wrist/fingers. Also when tackling, when you slow down your opponent always seems to be able to knock the wind out of you that much easier. I can't explain how this works scientifically, but empirically I've noticed these things during my 10 years of playing time.
And beyond just avoiding injury or getting pounded by a huge lineman, there seems to be a clear mental benefit in failing at full speed as well. Your body tends to remember the decision it makes, and it was right, it will repeat it. If it was wrong, it will avoid it. Again I have no scientific way to explain this, but I'll give this one my best shot.
I attribute this phenomenon to muscle memory. As an athlete, you will find yourself doing a lot of tedious drills. The point of this is to gain muscle memory for the basic skills you need for whatever sport and position. That's why drills tend to be easy, then hard, then easy, then hard, etc. Because you usually will build muscle memory for somehting very basic, move on, get used io it, then it becomes basic to you, and you have to move on, and etc. My observation is that drilling tends to be very effective, and my hypothesis is because it banks on muscle memory (which for many people is very effective). A lot of math people to do it too (I know b/c I used to be a mathlete). In school, we get drilled on fractions, times tables, etc. This is all because muscle memory is great for a quick and reflexive response.
This is why making mistakes (or failing) at full speed is important. Because failing at full speed enough times, will make you instincly know that it's the wrong thing. It means that you will be able to make the right decision faster, because your brain has been trained to see what's wrong. Maybe you won't instinctly know what's right but you'll instincly know what's wrong and if you fail enough times, logic says you'll eliminate all wrong options and therefore you will know what's right afterall. That's right there is an argument to fail fast. So you can get to the right option faster.
But just like with sports/math/whatever, some people "get it" faster than others. And some people develop that instinct after shorter periods of times than others. It really just depends on how smart you are, and after a certain point that is probably out of your control.
So segue into startups and real life... the more you make business decisions at full speed, the more likely that if it was the wrong decision, or a mistake, you'll build the instinct to avoid it.
The thing people end up doing wrong is overthinking and taking too much time on decisions. You'll never be able to internalize that decision process unless you're a super genius (which some entrepreneurs might be). So think about it, and go for it. This is why VC's encourage companies to go after high stakes really quickly. I think it's not only because that's how fund math works, but because it's how great companies are built.
And this principle of failing at full speed applies to life too! Try it next time, smarty! When you're lost and you have to decide to turn right, or turn left... next time don't think too much about it and just go for it. It will be better for you in the long run. Trust me.