I would suggest doing the last 1% first, but therein lies an infinite regress.
More practical: have a well defined checklist of must-do's. And a separate list of significant nice-to-do's.
Then wind up a project any time all must-do's are done, with however many nice-to-do's actually got done.
So the last 1% (10%? 25%) are optional nice-to-do's that can be scaled back without concern. The optionality of nice-to-do's pads schedules, making targets dates easier to hit.
More practical: have a well defined checklist of must-do's. And a separate list of significant nice-to-do's.
Then wind up a project any time all must-do's are done, with however many nice-to-do's actually got done.
So the last 1% (10%? 25%) are optional nice-to-do's that can be scaled back without concern. The optionality of nice-to-do's pads schedules, making targets dates easier to hit.