Bread-Bakers v006.n063.7

I am new to the bb list and have been baking bread (the old fashioned way)
for about 9 months.
While I have made bread from only a few favorite recipes, I have noticed the
recipes call for about the same amount of ingredients but vary from 1 - 4
tsps of yeast.
All of the breads seem to achieve the same volume so I am confused by the
wide variation in Yeast.
Can anyone help with an explanation.
TIA
Steve