Ramana Maharshi on Self Inquiry Practice duration

Question : How long should enquiry be practised?
Ramana Maharshi : As long as there are impressions of objects in the mind, so long the enquiry ‘Who am I?’ is required. As thoughts arise they should be destroyed then and there in the very place of their origin through enquiry.

If one resorts to contemplation of the Self unintermittently, until the Self is gained, that alone
would do. As long as there are enemies within the fortress, they will continue to sally forth; if they are destroyed as they emerge, the fortress will fall into our hands.