[njovin]

The next natural progression of this line of discussion between "the business" and engineering is for them to agree on a time range as an estimate. Engineering doesn't want to say it'll be done in 6 weeks, but they feel okay saying it will take between 4 and 20 weeks so this estimate is accepted.

You can guess what happens next, which is that around week 8 the business is getting pretty angry that their 4-week project is taking twice as much time as they thought, while the engineering team has encountered some really nasty surprises and is worried they'll have to push to 24 weeks.

[shiroiuma]

You're forgetting the part where the business expects the engineers to pull all-nighters so they can meet the deadline.

[skeeter2020]

it is still better to give a range though because 1. it explicitly states the degree of unknown and 2. no boss is going to accept 4-20 weeks, which means you start talking about how you can estimate with better accuracy and the work required to do so, which is a major goal of planning & estimation.