I think, there is a many nonsense about chakras in Western countries. I recommend to read the translations of the original texts of the East, not a new fictions of western wannabe "Masters".
Good books about are transalntions by sir John Woodroffe - Arthur Avalon - for example like Sat chakra nirupana, Paduka panchaka, The serpent power and so on. Or a good books are Shiva samhita a Gheranda samita. A good text from China is The secret of the golden flower, translantion by Richard Willhelm. All those books and many others are freely on the net.
There are two different paths on the East. The first is a paths to Nirvana (paramatman). It means ending the cycle of lifes in this world and and in spiritual worlds too.
The second is a paths to obtain spiritual powers (siddhis) and a better life in the spiritual worlds.
A good book about the second path is not from India, but from ancient China. The secret of the golden flower, a Taoists spiritual alchemy. Translantion by Richard Willhelm. But, there is Ajna chakra called e "Heavenly Heart" and chakra Anahata "fleshly heart".
Yogis they want an ending the cycle of lifes do a meditation about all chakras. They must cleen them and awaken the Kundalini (The serpent power).
Yogis they prefer the second way must open chakra. But it take many years mediations about a one chakra only (see The secret of the golden flower - about three months concentration on Ajna (in the secret of the golden flower called "heavenly heart) chakra for calming, then bring attention to the Anahata chakra (in the secret.... called "fleshly heart) by monitoring breath and meditation for years in this place ).
Swami Raghavanand for example wrote.:
"It is important to great deepen of one meditation. Not many meditations."
When a chakra is realy open, siddhis - spiritual power hidden in - begin to work. Untill yogi do not obtain siddhis, chakra is not open.
For example see chakra Anahata:
Anahat Chakra or heart chakra: If one contemplates (contemplation = a long term meditation) on the flame called vanlinga that resides in the heart chakra (anahat chakra), he attains knowledge beyond measure. He attains clairvoyance and can see the past, present and future. He can walk in air (khechari siddhi) and travel anywhere (Bhuchari siddhi). Through his clairvoyance he can perceive the yogins..............................................
Mistakes about chakras