The Ninety-Ninety Rule of Project Schedules - the first ninety percent of the task takes ninety percent of the time, and the last ten percent takes the other ninety percent.
Enough research will tend to support your conclusions.
Any given program will expand to fill all available memory.
Friends come and go but enemies accumulate.
Every solution breeds new problems.
When working on a project, if you put away a tool that you're certain you're finished with, you will need it instantly.