If your batter becomes too dry because of the different size of bananas then add about 1 - 2 tbsp dairy free milk to the batter while whipping up. (kiipfit.com)
Once you know the right size of banana to start with, you can skip the measuring cup and mash the banana right in your mixing bowl. (eatingcleanrecipes.com)
Yes, size of the banana does make a difference... but it's hard to quantify exactly how big is «too big» and how small is «too small», I think! (freshplanetflavor.com)