To get white and spotless laundry, you may also want to incorporate other laundry practices

Use a detergent that has whitening agents (like oxygen bleach or enzymes). Add a cup of white vinegar to the rinse cycle to help remove residue and brighten whites. Ensure you’re washing at the right temperature (hot water often works best for whites, but check care labels).
In short, yes, for light loads or using highly concentrated detergent, one tablespoon might be enough, but be sure to adjust based on your specific laundry needs.