Gold Bar puzzle


#1

Why can not we divide the bar into two pieces of 3 and 4 OR 2 and 5.
For example lets divide into 3 and 4.
Day 1 you 3 worker 4
Day 2 you 4 worker 3
Day 3 you 3 worker 4
Day 4 you 4 worker 3
Day 5 you 3 worker 4
Day 6 you 4 worker 3
Day 7 you 0 worker 3 and 4