Fat is the main energy source in dog diets, and so it's very normal for kibbles with a higher fat percentage to require smaller serving sizes - they need to eat less of it to meet their caloric needs. In the case of complete diets like most kibbles, any serving large enough to meet a dog's caloric needs is going to meet the rest of their nutritional needs as well, even if it's smaller than the recommended serving size for their weight (which it almost always is - most recommended servings on dog food are on the high end for most pet dogs).
As for whether you'd be feeding more fat total with the Large Breed vs. the ALS in that case, you do have a little hiccup with your decimal placement of the percentages. It should read: 3.625 cups food * .13 = 0.471 cups fat a day, and 4 cups food * .145 = 0.58 cups fat a day. So you'd still be feeding more fat daily with the recommended portions of ALS food, even though they're smaller. However, it's worth remembering that these percentages are only minimums, not exact numbers as it's easy for macronutrients to vary slightly between batches of food, so it's good to avoid getting too caught up in the exact numbers.
I hope that helps clear things up a bit. I personally don't try to get too bogged down in the numbers when it comes to complete, commercial diets following AAFCO (or similar) guidelines (obviously the exceptions are when trying to manage a medical condition with food or balancing a homemade diet), and mostly evaluate what brand/amount is working based on how my dogs look, feel, and behave. Saves me a lot of stress, because it's easy for me to get caught up and freaked out over minutia when my dogs are actually doing just fine.
As for whether you'd be feeding more fat total with the Large Breed vs. the ALS in that case, you do have a little hiccup with your decimal placement of the percentages. It should read: 3.625 cups food * .13 = 0.471 cups fat a day, and 4 cups food * .145 = 0.58 cups fat a day. So you'd still be feeding more fat daily with the recommended portions of ALS food, even though they're smaller. However, it's worth remembering that these percentages are only minimums, not exact numbers as it's easy for macronutrients to vary slightly between batches of food, so it's good to avoid getting too caught up in the exact numbers.
I hope that helps clear things up a bit. I personally don't try to get too bogged down in the numbers when it comes to complete, commercial diets following AAFCO (or similar) guidelines (obviously the exceptions are when trying to manage a medical condition with food or balancing a homemade diet), and mostly evaluate what brand/amount is working based on how my dogs look, feel, and behave. Saves me a lot of stress, because it's easy for me to get caught up and freaked out over minutia when my dogs are actually doing just fine.