Many of the mantras have been a A part of a Stotra or an Upanishad or even a fullfleged Sadhana or an Anushthana and have been under no circumstances meant to be used in isolation. Nonetheless, over a length of time, a few of the Pundits begun compiling the mantras https://hanumanshabharmantra00009.jiliblog.com/93357797/the-basic-principles-of-mantra-sadhna-expert