Is the mantra Om chamundaya namah safe to chant ?

I met a lady who is sadhak of lord Shiva and she's unmarried. she just do sadhana and help people in our community. I am currently doing sadhana of bhaairav for past 1 years and I know little bit of astrology too when I checked my chart I found out that Devi sadhana is meant for me but I haven't done any Devi sadhana except in navaratris I did 32 names of Durga(108 times) and siddha kunjika shotram(3 times)for 8 days. The thing is the day before yesterday I decided to visit the lady and ask for guidance she uses initution to predict things looking at grains of rice and hand and she too said Devi sadhana is good for me and when I told her about how I do my sadhana she made some few changes( which is beneficial ) and when I asked her which Devi should I worship she said chamunda reason she stated was that I had been doing bhairav sadhana that's why. so said to chant the name mantra of that deity but just 1 maala can I chant 'om chamundaya namah'? is it safe ?