Fountain.fm switching to only earning sats on select days for listening is kind of a bummer, but I guess you can't really complain too much about free sats. You can still earn some sats every day from listening to the promoted podcast.
Discussion
It was a marketing ploy all along. It still is even with limited days. Whatever the case if people like it they will use it as long as app usage is free. They add paywalls then you are just serving hardcore podcasters and listeners and not general public. This is where Ad revenue comes into picture.