Most f2p games I’ve played have event weeks or holidays on which special things happen.
What i think should be done, is have some event weeks where devs can try things out. IE: this week your characters regen after each fight unless they are KOed, this week iso earnings are doubled, certain characters skills could be temporarily altered temporarily, etc.
This way devs could try out new metrics and see how they affect purchase of resources to see if the permanent change would be worth while. The testing of temporary skill changes would allow the community to become testers as opposed to the devs relying on in house testing, which has proven insufficient in the past.