Nope. You can place a leaf in the water and leave it there until you get tired of looking at it. It doesnt matter if it decomposes or if you replace it with every water change.
If you do frequent water changes, you can either prepare your new water in advance, place the IAL in and let the water age a couple of days.
You can also prepare a concentrated solution in a 2 liter bottle with a bunch of IAL in some warm (not boiling) declorinated water, leave it to cure for a week and pour a few ounces of it when you do water changes. Keep adding leaves and water to keep your reserve going.