50% is 50%... 1 hour is 1 hour. It does nt matter when it is used the bonus is still the same and the duration is still the same.
A percentage increase is not greater or lesser at any given point. The numerical value of the increase might differ but the increase is still the same percentage, it doesn't matter if you are getting 50% more of 100 or 50% more of 10,000 50% is always 50%.