If all you have is a hammer, everything looks like a nail.
I draw a dichotomy between Hammers and Nails:
A Hammer is someone who picks one strategy and uses it to solve as many problems as possible.
A Nail is someone who picks one problem and tries all the strategies until it gets solved.
Human beings are generally Nails, fixating on one specific problem at a time and throwing their entire toolkit at it. A Nail gets good at solving important problems slowly and laboriously but can fail to recognize the power and generality of his tools.
Sometimes it’s better to be a Hammer. Great advice is always a hammer: an organizing principle that works across many domains. To get the most mileage out of a single hammer, don’t stop at using it to tackle your current pet problem. Use it everywhere. Ideas don’t get worn down from use.
Regardless of which you are at a given moment, be systematic because Choices are Bad.