One of the themes of Atlas Shrugged is one of the themes of my own philosophy: Don't overreach.
I say: If you exceed your abilities, if you try to do more than you can manage, then you will make more mistakes. More things will go wrong. If you do this too much it'll overwhelm your capability to deal with mistakes. That's overreaching: doing activities where your rate of making mistakes is too high for your ability to find and fix mistakes. Overreaching is bad, and pretty much all adult lives have tons of overreaching. The situation is so bad people just give up on correctness and try to muddle through life putting up with many unsolved mistakes.
Rand doesn't say that. But she says something related.
In Atlas Shrugged, the world has a bunch of nasty problems. Dagny tries to ignore them and run a railroad anyway, but the problems are pretty damn overwhelming and this doesn't work out in the long run despite how amazing Dagny is. What should she have done instead? Retreat from a world where she and her values aren't wanted. Give up the railroad. Give up on big accomplishments in screwed up world. Live her own life. Keep it simpler and smaller, like how they live in Galt's Gulch. But keep it pure with no corruption. Live in a way where everything works and there's no compromises, downsides, disasters, people working to make your life harder, looters stealing from you, taxes draining you, and so on.
In other words, Atlas Shrugged says to scale back your ambitions to projects which are reasonably possible in good ways – without tons of stuff going wrong. That's what John Galt and his allies do. They won't participate in corrupt, broken projects. They will only live life in ways that work. They'd rather have a single hand-tooled tractor in Galt's Gulch, or a little farm, or a few barrels of day of oil production, or a cabin instead of a skyscraper ... as long as it's fully theirs, it's fully pure and proper and correct ... there's nothing broken or wrong or bad about it.
In other words, it's better to have less without errors, corruptions, sacrifices, and moral compromises, rather than to have more at the cost of your soul or the cost of it not actually working right.
It's also like how you should learn things in general (e.g. typing, martial arts moves, or video game techniques): do it slowly and correctly and then speed up. Do not do it fast and wrong and try to fix the mistakes when there's a bunch of them. Speed up gradually so you only deal with a few mistakes at a time and keep the mistakes manageable.
In the introduction of Atlas Shrugged (35th anniversary edition), Peikoff quotes Rand's notes:
Her [Dagny's] error—and the cause of her refusal to join the strike—is over-optimism and over-confidence (particularly this last).
Over-confidence-in that she thinks she can do more than an individual actually can. She thinks she can run a railroad (or the world) single-handed, she can make people do what she wants or needs, what is right, by the sheer force of her own talent
Overreaching isn't just for beginners who try to act like experts. Even a great hero can overreach.