Work expands so as to fill the time available for its completion.
Choosing how much time and resource you want to dedicate to any given project or task is one of the most important things a manager can do. As Parkinsons law predicts, work complexity will expand to occupy all of the time and resources you give to it. If you allocate an entire team $1 million and 1 year to solve a problem, would you expect them to come back in a month having only spent $5? No. The team will always believe the task cannot be simple, and unknowingly set themselves up to spend the resources and occupy the timeline.
Big problems need to be allocated just enough time that resolution will be efficient. Small tasks should never be given too much time.
Sometimes my best presentations were the ones I only gave myself an hour to prepare… I simply wasnt given the time to complicate it. I had to stick to the big, important, meaningful content.