Should I practice a single mantra or multiple?

I've received empowerment for Seven Line Prayer & have been practicing it consistently ever since. Once in a while, a thought arises that I would like to practice other mantras for 'worldly situations', e.g. Green Tara when there is a situation of illness & disease Should I concentrate my efforts on a single practice? Or is it beneficial to 'spread out' my practices. My goals are stream-entry as a layperson