As a data point, flying out of Venice today, Ryanir would not let me pool my 2x20kg and 4x10kg purchased total weight of 80 kg across my three physical bags with an actual total weight of 71kg.

I had to purchase another suitcase and check in a tiny pointless bag.

i asked what is the minimum bag I had to check to pool over these dummy bags and the answe was anything that zips.

This policy is completely insane and not how I read the bag pooling instructions on their website. There is zero reason I had to check in two ghosts bags, the weight was exactly the same. I paid for 80kg with no one bag exceeding 32kg, it shouldn't matter if I did it with 3 or 6 bags.

I sent ryanair an email, I don't expect anything to come of it. I asked them to explicitly clarify the rules because it is ambiguous. Or the checkin person was having a bad morning.