My own theory relating to difference in number between systems could relate to the fact that these other or additional ones are more minor chakras wheras the systems that number fewer jus list the major ones. remember that chakras are generally understood to be the points where the nadis converge and diverge.They are centres of consciousness.
The suggesstion of 3 out of 7 are usually blocked sounds like the usual new-age interpretation stuff on chakras that i tend to not take seriously-honestly sounds like the usual new-age nonsense. It usually has no basis in science or on ancient yogic texts or authentic traditional yoga systems.I don’t trust it as credible source. Everyone has blockages. BUt The truth is ultimately found within yourself.
Any of these books should give you a credible summary of the chakra system.
Layayoga: The Definitive Guide to the Chakras and Kundalini by Shyam Sundar Goswami
The Serpent Power: The Secrets of Tantric and Shaktic Yoga by Arthur Avalon
Kundalini Tantra/2009 Re-print by Swami Shantanand Saraswati
I don’t have the first book but i’ve heard it as being credible.
There was one book that sounded like new-age nonsense which i actually threw out- it sounded wishywashy to me. althoughi am free to be corrected here if i may be mistaken.
Kundalini & the Chakras: Evolution in thi… by Genevieve L. Paulson out which is this book-
This one appeared suspect- like i say ,new-age nonsense.As i say i binned it as i did/could not trust it.What the author also said about having to protect yourself about other people’s draining negative energies did not resonate with me.She sounded to me like she had a few issues of her own, like un-enightened or not sympathetic enough to the plight of other people , but like i say that was just my own perception.I don’t usually throw books away but this one did not resonate with me.The author did not sound very altruistic or compassionate forr the sufferings of other people and advised steering clear i believe in case one’s own energies or something like that were drained.And then there wer the enrgetic map pictorials too, no reference to any of the ancient text of i reckon- It just seemed wishy washy new agey.
BTW weakness or blckages in the chakras, the subtle nervous system, the nadis,the pranayamkosha could manifest mentally,emotionally and physically,psychically,energetically- on all levels.