I don't see why it wouldn't be. Conscious thought is only the tip of the iceberg; even Western thought has a long tradition of noting that Eureka moments come during periods when you are not rationally engaging with the topic. See for example
That is the belief. But deep meditation is elusive. You need to understand the relationship between yourself and your Mantra.
One of the best explanations of Mantras and meditation are by Dr Robert Svoboda (for any audience more familiar with English than Sanskrit/hindi). Granted he trained under an Aghori which isn’t traditionally the path most folks would take. But his explanations are exemplary.
