[lbraasch]

The last 10% has little to do with the number of remaining items, and all to do with the type of tasks and mental blocks. Project fatigue sets in.

Within the last 10% are small details pushed aside as the pace was chugging along for the other 90%. Seemingly trivial problems are hidden until the end, during which, developers/engineers are most eager to move on to the next mentally stimulating new project.

I think there is a reason why in schooling, 'A' level work requires a completion of that last 10%.