I'm not baking anything but question about leaven plz?

More yeast in a recipe, as in about double the amount gives the bread or other baked goods a distinct beer flavor and smell.

Doubling the amount of baking powder or baking soda or both, gives the baked goods a bitter chemical flavoring similar to commercial products but more pronounced.

It is more the flavor and smell of the baked goods that is changed, not the leavening power of the chemical compounds or the yeast. To me it is just a waste of good ingredients!!

There are a lot of things that cause a leavening effect.

Yeast - the amount doesn't have to be precise, the result will be the same

Baking Soda - If you use too much, it will effect the taste, but not the amount of rise. Baking powder is an acid neutralizer and by reducing the acid in other ingredients, it allows other leavening agents in the recipe to work (eggs, baking powder, etc)

Baking Powder - Same thing. Too much and you will taste it, too little and you do not get the proper rise.

The reaction that causes leavening isn't really dependent on how much is used--it might cause your baked goods to rise too much, or it may just ruin them. Yeast eats sugar at a rate dependent not on how much yeast there is, but how good the conditions are for its growth. Adding more won't help anything happen faster, and might just cause too much swelling in what you're making. But what isn't used by the yeast's reaction will just sit there and do nothing if it has nothing to eat.