I use IALs in most of my tanks as it gives my wild bettas somewhere to hide and seems to induce bubblenesting and territorial behaviour in my males.
For use with my splendens, I sometimes boil up a few leaves and create a concentrated extract that I add to their water after a water change. But mostly, I put a whole leaf in each week, and take it out once it starts to sink and go soft.
In my wild tanks, I let the leaves sink down to the bottom and break down naturally. I for one, have never noticed any discernible ammonia spike due to the leaves breaking down in the tank, and I've found this encourages the growth of microorganisms that helps feed my fry.