Work expands so as to fill the time available for its completion.
I just stumbled upon this adage and, while I believe it is absolutely true, I have to say I enjoy it much more the way Paul A. Clayton elaborates on it on the Real World Tech forums:
Ordinarily, work is a gas, expanding to fill its containing time. Under intense pressure, supercool it and work can become a coherent liquid, but it is extremely difficult to get solid work. If one puts a enough energy into work it may become a plasma, but then one really wants to be sure it is safely contained (uncontained work plasma “will consume everything around it”).
[Source: Real World Tech forums]
Not as polished, definitely not as memorable, but still extremely true.