I don’t think I can follow. So let me explain it in a different way.
Current RS numbers are 16/20/30/38 and choiceof 6 (both might get changed in the futures to match the required throughtput with the remaining number of nodes)
This combination of RS numbers and choiceof factor will select 38x6 nodes in total. Now each subnet has an equal chance to make it into this selection group. If there are 2 nodes on the same subnet they get 50% of that rate. The 2 nodes on the same subnet will never get selected at the same time.
The rest with the choiceof comparison happens after that. The fast and the slow node need to be part of the initial selection group to get to the comparison part. At that moment the success rate will change the outcome. The slow node might get matched up against a fast node and kicked out of the final set of 38 nodes. The fast node on the other hand has kind of a garantee to always be part of the final set and because of the 6 times bigger initial selection it gets 6 times more uploads. With the second node on the same subnet the initial rate gets cut in halve.
In production the RS numbers are still 29/35/65/110 and choiceof 2. Similar math just with a maximum factor of 2