This is my guess based on Bryan Caplan.
I mean my own IQ is small. But I also saw that with lots of work, I could get father than people with genius IQ's. But I also have a very low ceiling of how far work can get me. And I have very high respect for smart people. My learning partner in Talmud finds things that I would never see even I would learn the page a thousand times. What happens in Lithuanian yeshivas is there is a kind or appreciation for these two factors coupled: (a) זיצ פלעש the ability to work--in yeshiva jargon that is called the ability to sit and concentrate for many hours and (b) smartness.
But what we learn from this is simple. For someone like me that is not smart, the main thing is to concentrate on one thing-- if you want to get anywhere. I mean the "smartness thing" there is not much I can do anything about.
And this idea of concentrating on one thing at a time has been a great help for me. For example in understanding Tosphot I have found it useful to stay on one Tosphot for a long time, since it seems to me impossible to penetrate the deeper meaning of Tosphot without doing this. and even very smart people have a disadvantage in this because they are so smart they think they understand Tosphot right away when they have completely missed what is going on. Smartness I have seen can be terrible disadvantage.