Hi Fara, great question.
If you infuse it longer, it will become more potent.
Feel free to do this! If you choose to infuse it longer, it’s helpful to add vitamin E oil after you strain it to prolong shelf life. Rosemary oleoresin works well too. The length of infusion time depends on what method you are using (low heat in a crock pot, in a sunny window, warm bath, etc).
I have left herbs in oil for weeks to even months at a time, with great results. I usually add it to a crock pot for 48 hours on low heat if I am in a rush to have it ready.