Says Who? No study has ever been done to say one is better than the other. Mice are closer related to ASF than the Norway rats we feed.
And the 15% rule only pertains to yearlings. No reason to ever feed anything over 100g per meal once a week. This WILL lead to an obese snake by time their 4 years old.
OP, feed what snake wants, if one mouse isnt enough, you can try a wean rat which is about 45g in size or give 2 mice per week. Its all about what works for you and what the snake eats.