You can apply daily or every other day. The most important thing will be to keep the tank hospital clean. This will require at least changing the papertowel daily. Scale rot can take awhile to heal. You may see results By the next shed. But it could also take much longer. It doesn't seem to be a bad case. But watch for it getting any worse. The trick for you will be keeping up humidity without the tank being damp or wet.
I agree soaks can be counter productive. If everything was right with husbandry you shouldn't have needed to do soaks or should do them.
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