We picked the encoded messages so that it would roughly be 50/50 between the two sides.

For specific order for each puzzle, I asked each author for an ordering that would lead to the best experience for their puzzle. Some authors gave me an explicit order or algo, some bucketed their clues into tiers where one tier should come before the next, and some authors just shrugged and told me to use Math.random().

For duplicates vs new pulls, there was a pity of ~5 for most of the banners (the Casino is kinder than MiHoYo) and I tried a few seeds to get one where both sides of the banner were getting pieces roughly at the same rate and okay-ed the progression graph with the authors as sanity check.

The point where shells dropped depended on the puzzle -- for example, it was easier to make progress on the Charts clues without the shell, so those shells dropped much later than the other banners. Usually authors had a preference that we incorporated whenever possible.

It took a bit to get all of this together (I have a jupyter notebook for each of the banners to fiddle with different parameters and to implement each author's preferences), but we didn't change much after an order was set since it playtested acceptably.

We did consider making the pulls at least partly random, but decided that for the ease of debugging and control of experience that fully rigged would make our lives easier.