The feats for Crafting both Scrolls and Potions both state
Scribing a scroll takes 2 hours if its base price is 250 gp or less, otherwise scribing a scroll takes 1 day for each 1,000 gp in its base price.
Brewing a potion takes 2 hours if its base price is 250 gp or less, otherwise brewing a potion takes 1 day for each 1,000 gp in its base price
A Valet Familiar gains the Cooperative crafting feat which says.
Benefit: You can assist another character in crafting mundane and magical items. You must both possess the relevant Craft skill or item creation feat, but either one of you can fulfill any other prerequisites for crafting the item. You provide a +2 circumstance bonus on any Craft or Spellcraft checks related to making an item, and your assistance doubles the gp value of items that can be crafted each day.
For context, my group is using the Downtime rules which uses 8 hours of time for each action meaning you could craft 4 potions/scrolls during this time as long as they cost less than 250gold. So the question is by RAW could the crafter craft 8 potions/scrolls instead of just 4? Is this also RAI?
My GM disagreed saying the Familiar doubled the possible gold crafted during one session, but you could still only have the same amount of sessions but if you went over the 250 value it went up to the full 8 hours. IE if you craft a potion under 250gold it still takes 2 hours but if you go over that it takes the full 8. The way I read it you double how much you can craft so either you can craft an item in a single hour, or you can craft up to 500gold worth in 2 hours.
Best Answer
Cooperative Crafting increases the value of what you are crafting per day, not the amount of things being crafted in any given time, nor the amount of time you take to create a potion/scroll. Valet familiars gain the feat even if they do not meet the requirements.
If your crafting limit was 1,000 per day, with a valet familiar, this limit is now 2,000 per day. But what the feat helps with is the Crafting Progress you make each day. If you would take 10 days to craft a 10,000 gp magic sword, with a valet familiar helping you, this task now takes 5 days.
For potions and scrolls, that are normally 250 gp per 2-hours work, it doesn't become 500 gp per 2-hours, but means that your daily progress will be limited at 2,000 gp. Which makes the feat only useful for higher level scrolls or potions crafted using a higher level caster level, as potions are capped at 3rd level.
You cannot craft two items at once, nor you can craft twice the amount of potions. You are still limited by other rules:
Potions and scrolls take 2 hours per 250 gp on their price, or 1 day per 2,000 gp on their price.
Other magic items take 1 day per 2,000 gp on their price.
The GM could house-rule that it also increases the 2-hour limit for potions and scrolls, but that's not what says on the feat.