Hosteter’s law says projects you undertake will always take longer than you think, even when you account for adding time.

And yet another adage is "the time you allot to do any task is how long it will take," if you will work within the time you are given.

For example, if decide to spend one hour, it will take an hour and a half, but if you plan for an hour and a half it will probably take 2 hours. Yet if you allot 2 hours (thinking it will take one) it will take more time. But even if you allot four hours you will stretch the project into the four hours, and probably not be done.

Reality seems to fight back in an exponential fashion, in which we always lose. Planning seems not to coincide with how we see reality.
Yet the conundrum of not planning is never to achieve.