A no-parking sign is an implicit rule. It relies on people choosing to obey it, with a vague threat of a potential fine. A tree planted on a sidewalk is an explicit rule. You can't park there, mate. A traffic light asks you to stop. A roundabout makes it physically difficult to not slow down.
How to Give Up Your Life’s Work
I count a project as working if it makes money, teaches me something, or gives me real enjoyment. If I go three months without getting any of those from a project, I stop.
cheap to start increases supply, cheap to stop weakens a foundation