Manasic japa, like other kinds of mantra yoga, is often recommended for yogis who have weak bodies or physical limitations and may struggle with the demands of Hatha yoga practices. It is said to be an easier, quicker and more certain way for such yogis to attain Self-realization.
Once all three types of japa are mastered by the yogi, some advise that a combination of all three should be practiced. The mind is said to respond well to the variety. For example, manasic japa may be practiced until the mind starts to wander, then the yogi can switch to vaikhari japa.
Traditionally, manasic japa is considered to be focused in the heart area, as opposed to the vaikhari, which is focused in the throat. For it to be effective, and have a power beyond that of simple introspection, it is suggested that the yogi know the power in the mantra that they are repeating. They should repeat the mantra with devotion, love and feeling. This mantra may be the name of a deity, or it may be a mantra, such as the Gayatri mantra, which is said to brighten the intellect.