Hello there, RiffRaffRiot! Oh, I know precisely what you mean, love. It's an absolute blimey, isn't it? My husband always says it's like a race against time with bananas!
I've found that hanging them up on a banana hook, if you've got one, really does make a difference. Keeps the air circulating, you see. Also, storing them away from other fruit, especially apples and tomatoes, is spot on advice. Those ethylene gas producers are the culprits! Hope that helps your smoothie game, chuck!