Is it true that low-value votes should come before the 15 minutes timeframe and why?
The advice in the question sounds like it is made with an aim to maximising curation rewards.
In order to maximise curation rewards there are three main factors:
- Position in the voting timeline - You want the payout on the post to be as low as possible when you vote (it is the payout that is important when you vote, not the prior number of voters) which typically means voting earlier than 15 minutes.
- Early voting penalty - You want to make the early voting penalty as small as possible by voting at or after 15 minutes.
- Posts with large rewards - You want to vote on posts which end up with large rewards in comparison to the post payout at the time when you voted.
The first and second of these factors are conflicting. You want to vote before everyone else, but without losing too much of your curation rewards to the early voting penalty.
In the end it comes down to a trade-off. How much of your curation rewards are you willing to send back to the reward pool through the early voting penalty in order that you gain curation rewards by being early in the voting.
Whilst the best moment to vote varies between all posts, typically the trade-off points towards voting before 15 minutes to maximise curation rewards.
The smaller your vote, the higher the benefit of being early in the voting timeline (since post payouts grow over time) and the earlier you will want to vote to maximise rewards. However it is a complex calculation and well worth sitting down with the mathematics to make sure you understand the trade-off.