rsha Vidhya practises are Poojas practiced by the Guru Parampara, without questioning the origin/source of it. It is merely done with full respect to the Guru Parampara as accepted and practiced by Guru Parampara.
A Pooja or a Yantra is done with an attitude of appreciation and reverence that it worked for the Guru and ParamaGuru and so on and henceforth will work and be fruitful in the same manner to his descendants also.
Palm leaf yantra (olai) is one such practice. Generally, a palm leaf is used to invoke divine blessings. The yantra which is unique to our Guru Parampara is written on the top surface of the leaf. After doing Poojas to the same, the leaf is boiled in a cup of water, Once the water reduces to 1/3rd of its level, the water is supposed to draw the divine powers of the leaf.
Upon consuming that holy water, one gets a lot of beneficial effects like good memory power, removes fear arising out of evil influences & helps the person come out of vices over a period of time like smoking or drinking and it gives him mental peace and tranquility.