I found several post explaining how to upvote smart:
1.If you upvote before 15 minutes you give 99.94% to the author and get 00.06%
2.If you upvote after 15 minutes you give 50% to the author and receive 50%
3.I f you upvote after 30 minutes you receive 100% curation reward
Who can tell if this is ture?