by Swami Sivananda
Any one of the Vidyas should be selected according to one's own option or choice.
Vikalpo'visishtaphalatvat III.3.59 (418)
There is option (with respect to the several Vidyas), because the result (of all the Vidyas) is the same.
Vikalpah: option; Visishtaphalatvat: on account of (all Vidyas) having the same result.
The most important Vidyas are: Sandilya Vidya, Bhuma Vidya, Sat Vidya, Dahara Vidya, Upakosala Vidya, Vaisvanara Vidya, Udgitha Vidya, Anandamaya Vidya, Akshara Vidya.
One may follow any Vidya according to his option, and stick to it till he reaches the goal, as the result of all Vidyas or the goal is the same, namely the realisation of Self or Brahman. If we adopt many, the mind will get distracted and the spiritual progress will be retarded. When the Brahman is realised through one meditation, a second meditation would be purposeless.
Therefore, one must select one particular Vidya and stick to it and remain intent on it till the fruit of the Vidya is attained through the intuition of the object of meditation.