It would be a super-weak and "waste" of an option to use for eternal potion (granted, if it's down time it's not likely to want to use anything else, then again if it's downtime you wouldn't need eternal Crafter's Fortune in the first place).
Do you make a crafting check for each individual item you make or something?
I think it makes really good sense to bundle crafting progress of all items using the same craft skill into one check, especially since many of these items can be very low price and hence crafted many at once, which would be tedious to roll individually (if one did rolls, at least).
In fact, I consider the DC*check formula used for determining progress to be silly and a hassle. It makes things better in multiple ways if one just took check*check for progress, as long as they can meet the DC to craft when taking 10.
It makes crafting much much easier.
