The ultimate productivity hack is saying no.
Not doing something will always be faster than doing it. This statement reminds me of the old computer programming saying, “Remember that there is no code faster than no code.” 1
The same philosophy applies in other areas of life. For example, there is no meeting that goes faster than not having a meeting at all.
This is not to say you should never attend another meeting, but the truth is that we say yes to many things we don't actually want to do. There are many meetings held that don't need to be held. There is a lot of code written that could be deleted.
How often do people ask you to do something and you just reply, “Sure thing.” Three days later, you're overwhelmed by how much is on your to-do list. We become frustrated by our obligations even though we were the ones who said yes to them in the first place. 2
It's worth asking if things are necessary. Many of them are not, and a simple “no” will be more productive than whatever work the most efficient person can muster. More effort is wasted doing things that don't matter than is wasted doing things inefficiently. And if that is the case, elimination is a more useful skill than optimization. I am reminded of the famous Peter Drucker quote, “There is nothing so useless as doing efficiently that which should not be done at all.”
Taligent's Guide to Designing Programs. Hat tip to Kevlin Henney
Even worse, people will occasionally fight to do things that waste time. “Why can't you just come to the meeting? We have it every week.” Just because it is scheduled weekly doesn't mean it is necessary weekly. You don't have to agree to something just because it exists.