Amount of yeast in sweet rolls

[storm]

I have two similar recipes for sweet rolls, each requiring 4 cups of flour. One recipe calls for 1 package of yeast, while the second one needs 2 packages of yeast (and can be refrigerated overnight for the second rise). Why the difference? Will the second recipe yield a fluffier product, or will it taste yeasty?

[thebighat]

I pay little attention to discrepancies like that, though the fact that the second dough is retarded may be the reason it calls for extra yeast. Actual bakers figure out yeast amounts as a percentage of the flour weight, and that will vary according to the type of dough being made. A lean straight dough bread might use from 2-3% yeast, based on the flour weight. That percentage creeps up as the dough is more enriched with eggs, fats and sugars, and might top out at 6-7%.
On the other extreme are doughs made with thin overnight starters called poolish, which have a fraction of a percent of yeast. If I'm confused by a recipe in cups and tablespoons, I convert it to weights, and using my encyclopedic knowledge of the baking arts, make a wild guess as to a percentage for the yeast. Seriously, you get a feel for it after a while, knowing the range of doughs and what they need.

[thebighat]

One other thing about weights and percentages- it is far easier to compare one dough to another when you have the percentages because then you are comparing apples to apples, so to speak. I've been playing a lot with danish this past week and find that knowing that one dough is 12.5% sugar and another is 6% helps me make judgements about sweetness and tenderness without having to make the dough to find out.