About voting windows first.

First some clarification: since HF25 there are four active voting windows. First three affect weight of the vote (its share in curation rewards allocated to post during payout), last one overlaps with third window and affects power of upvotes.

• up to 24 hours after post creation the vote has maximum share of curation rewards linearly proportional to power of the vote (you can see the value as weight field in effective_comment_vote_operation virtual op in any block explorer - it will be equal to rshares - power of the vote)
• next 48 hours (day 2 and 3) the vote has half the maximum share
• after day 3 until payout the vote gets 1/8 of maximum share
• in last 12 hours before payout, on top of being part of third window, the power of the vote diminishes linearly down to zero right before payout (value of rshares will drop and on top of that weight will be 1/8 of that value due to being part of third window)

Let's say alice and bob have the same 1000 HP, they vote while having full voting manabar and the post receives 6 HBD payout making curators' portion of reward 3 HBD. They are the only voters.

• alice votes in first day (1000HP power with 1000 shares), bob votes in second day (1000HP power with 500 shares). Since alice has twice as many shares as bob, she gets 2 HBD and bob gets 1 HBD
• alice votes in fourth day (1000HP power, 125 shares) and bob votes in fifth (also 1000HP power and 125 shares). They get 1.5 HBD in rewards each, since they have equal shares.
• alice votes in first day (1000HP power and 1000 shares), but bob votes 6 hours before payout (500HP power and only 62.5 shares). Assuming the post somehow still got 6 HBD in rewards, alice will get 1000/1062.5 of 3 HBD = 2.823 HBD, bob gets 62.5/1062.5 of 3 HBD = 0.176 HBD (the rewards are actually paid in VESTs, so precision is better, but whatever crumbs remain from division is added to author reward)

Now back to the topic.

The size of voting window is double edged sword. At first, when the change for HF25 was announced, I was skeptical. I thought that making vote shares depend only on power of vote (within the same window) will result in people voting for whatever, since it won't matter where they allocate votes. All relations are linear to your stake. But that was wrong. The voting windows are the key. The curator receives most rewards if they dig out post so good, that other voters won't mind voting for even out of optimal window. They can receive many times their usual curation reward if they manage to attract a whale. It also promotes building solid follower base to share posts with through reblogs.

Widening first voting window will allow more people to get full vote shares, thus reducing potential curation rewards for those who voted early (in first of above examples bob would still be in first window and the rewards would look like in second example, both 1.5 HBD, shifting portion from alice back to bob). Of course you could argue that the alternative is that bob would not vote at all, reducing overall reward for the post. That might be the case, although alice would be in the same position (post would be worth half, but she would be the only voter receiving all curation reward, which would be 1.5 HBD), only the author would be affected.

I'm not entirely convinced the deciding reason for posts "disappearing" after first day is because optimal voting window closes. When you look at posts sorted by creation date (most views in front-ends), you see fresh posts first, ranking in hot and trending also is heavily affected by how fresh the post is (otherwise posts that had more time to accumulate votes would always be first). So it might be the fact that older posts have to constantly battle more and more new content that they get pushed further away from voters' eyes.

I do agree though, that some content needs more time to digest, wider voting window would help such authors. So in the end I can't really tell if I'm for or against that idea, there are solid arguments in both directions :o)