Whether working time 8 hours or 10 hours per day will be more efficient and productive?

surly8 hours more efficient

I think8 hour is efficient to compare10 hours, because the employees will be fresh and happy it means happy employees better productive.

I think8hours will be more efficient

8 hours work is much Efficient as compare to10 hrs work 

Generally I agree with these other gentleman8 hours , the reason is ,  human error factor is greatly reduced because the employees keep a fresher mind , body and soul . A happy employee is a productive and loyal one .

1) I presume that, the targets/achievement is same for each comparison. In that case, productivity of8 hrs is  better than10 hrs work.

2) If you want to compare the duration8/10 , then, working for10 hrs is good as the task can be completed early and the resource can move to next job. 

it depends on the labors, some labors can work effectively10 hours but some can not