As someone who used to take about 200 flights/yr before Covid (a bit less these days), I long ago came to the conclusion that’s a question that can do you no good - pointless expectations, much unpredictability, and situations that can change any time.

If you are vulnerable to downgrades or idb (eg no status+cheap ticket), worrying about it won't exorcise that particular devil. If yo think you are the type of customers who might once in a while benefit from an oversold flight, don't try to anticipate it and let yourself be happily surprised and grateful if your lucky star ever strikes. Do yourself a favour, just don’t ask yourself, pick seats you’ll be happy with whether flight is empty or full and live happily!