Here are some aphorisms that I think upon, usually during meetings with grumpy managers.
It takes the same time to do a project right as to do it wrong
You just spend the tine in different places. You can rush through coding without any planning, but you will spend a lot of time in front of the debugger, and maybe have to throw your code away and start over when you understand the problem better. Or you can do thoughtful design, code at a deliberate pace, run your unit tests, and be done. It comes down to a lifestyle choice.
The most dangerous thing in the world is a half-understood Harvard Business Review article
There's an HBR article that says, essentially, "All other things being equal, getting software done sooner results in greater revenue." This one paper is the cause of so much misery for development teams. Managers love to use this article as an excuse to pry the software out of development and jam it into production before it's finished. They never read the "all other things being equal" part of the article.
There is an HBR article that says, "Pay is not what motivates employees the most." There are managers who read this article and think they can overwork and underpay their employees. They don't read the part about what does motivate employees, like empowerment, recognition, and work/life balance.
The most pain is inflicted when the manager hears a summary second-hand, and doesn't even know he has only half the advice. He thinks, "There's an HRB article that says you should ship the project as early as possible", or "HBR says employees don't care that much about pay."
When everything is important, nothing is
Ever have your manager tell you on Monday to work on this, because it is the most important thing, and then tell you on Tuesday to work on that, because it is the most important thing. And then you ask him to choose which is most important, and he says they both are? That is what a weak manager does when he doesn't want to make a decision. There must be a most important thing, the thing to finish first.
If everything is important, if everything is an emergency, then nothing is really important, because your manager will blame you for what you didn't choose, no matter what you did choose. If your manager behaves in this way, it's a good time to get your resume updated and start looking for work.
The 90/90 Rule: The first 90% of development takes 90% of the time, and the last 10% takes the other 90% of the time
Oh, how many times has a developer said he was 90% done in one month, only to spend a second month on that last pesky ten percent? You're 90 percent done with the part of the task you know about. Generally that's about half the task. It's a very mature organization indeed that can correctly estimate completion percentages. Your best chance is to estimate things using a consistent process, and then consistently record how your estimate matched reality. Then you can de-rate future estimates until your estimation process matures.