How much yeast to use when baking bread

One packet of dry yeast per 3 cups of flour

0.5% of the weight of the dry flour in the recipe.

For example, for 500 grams of flour, use about 2.5 grams of yeast. This is just under 1 teaspoon.

A packet of dry yeast is about 1.25 teaspoons.

A tablespoon of granular yeast is 10 grams of yeast.

A teaspoon of granular yeast is about 3 1/3 grams

If you are not patient, use more yeast if the dough is heavier (with more water, or whole wheat or bread flours), or you have cooler rising temperatures and you want a higher or quick rise.

Personally, I would go with patient, cooler rises with long rise times (say...65 degrees fahrenheit, and 12 hour rise times) - this leads to full, complex flavors and breads that keep well.

Recipes - well designed recipes - will provide yeast proportions, and are good starting points. With bread baking experience, your changes (such as providing longer rise times, or adding in other grains), will provide you clues for changing the proportions of yeast.