Indian Almond Leaves - How Long To Leave In?

[ADsnail]

They're supposed to be left in indefinitely as everyone nibbles on them and they break down to improve the environment. But I have one in a betta tank with 3 snails and no one is eating it. If they tried, they'd probably fall right off because it's so thin and flexible by now.

Meanwhile, it's getting a bit green on top. Time to start a new one?