While it's human nature to grab the biggest prize that you can afford
All prizes are equal. There are no prizes bigger than others, they are all zero, hence the name net0.
BUT grabbing the top one is way easier for everyone (we've tested this a LOT, see attached image)
Always tops method:
In the top image when you arrive you know that all you have to do is check the 4th chest and contribute accordingly.
Your suggestion:
In the bottom image, you have to decide which chest you should or shouldn't take based on the unknown rune needs/desires of other players, then try and figure out which one was already claimed by the other 3 players by mousing over chests until they line up, and then contribute appropriately.
While it's a bit quarrelsome, if you already have too many Runes of a type, why ever would you want even more? Claim the largest of the NON-Rune chests. You can always ANTE UP, several hours later, if some of the Rune Chests aren't claimed.
You don't. If you have too many [Needles] runes and take the top chest, you don't end up with "more" runes, you end up with fewer.
E.G. Pay 7 and get 3 back. It's a simple and easy way to turn otherwise worthless runes into 15 KP each.
UNLESS you're grabbing the top chest so that you can burn off a bunch of excess Runes, at 15 KPs each (rather than 10), without bumping anybody (you only need about 25 Runes to fill a Wheel), in which case I'd expect to see a significant overpayment for the top chest
What? there is no "overpayment", and why would there be? This is "Net0", not "Lose KP"
The top chest, just like every other chest has a value of (15*runes + 20*bigkp instant +5*smallkp instant) and each chest should always be claimed for exactly that much. Unless you're talking about a rune swap? We do this where advanced players will add [30] extra runes above the cost of the top chest on each others wonders (arranged in advance)
Again, if a player actually
needs runes, a much more effective method is to tell your FS that you need them. If no one knows then how can they guess which chest they should take?
There's simply no way to know if the top spot(s) should be held open for anyone, and for how long. Especially given your proposed 24h time limit how are players to know what to do when they log in, open the wonder, and (after figuring out what's going on) see that the top or second from the top chest is open? Do you take it to help out the wonder owner or leave it "just in case" a small player needs/wants the runes (more than you want to convert your excess runes to KP)?
Also, under your 24h system what would happen when the time is up and the top 2 of 7 chests haven't been appropriately paid for? If it was the bottom 2, no biggie, ~10 KP and maybe a rune, but if it's the top 2 chests? In the example above that would be a 95 KP loss for the owner.
Think of it like trades. Sometimes new tiny cities complain that there are no trades for them to take when they should be the ones posting and asking for trades since other players can't possibly guess what you want.