India is more akin to a continent than a country and to see everything on one tour of India is practically impossible, so it makes sense to split your India experiences in to shorter trips.
Many people choose to dip their toes in to India with a short India tour of a 5-7 days to experience the so-called Golden Triangle - Delhi, Agra and Jaipur. This is a great introduction to India and includes the great Moghul Palaces including the Taj Mahal.
An India holiday can be taken as a short one-week break, as a stopver en-route to other destinations such as South East Asia or in combination with an Indian Ocean island beach.