Earlier quoted context omitted.
I feel like if that task took 8 days you’d end up having to explain everything that happened and why it couldn’t be done in 1.
What would you rather - it took 8 days and you said it would take 1-8 days, or it took 8 days and you said it would take exactly 4 days ? In any case, there should be absolutely no problem explaining why it took 8 days if it really did.
The fact you even had to say that part points to the management problem at hand. Not only are you trying to keep idle time low, you're trying to estimate essentially unknown timelines, and you have to think about whether people are even telling the truth or padding hours where they feel they can.
I just think the range is too wide. Sure anything can be a 1 day task (potentially just an easy solution to add in, or some variables/settings to change, etc). And any 1 day task could be turned into an 8 day task (anything from refactoring unnecessarily, all the way to just walking the dog too frequently). I'm left wondering, how long should this task have taken?