Preconditions for fana or samadhi

To enter fana or samadhi, one may need one or more 45 minutes of meditation, some experts say sometimes all night long may be needed to enter fana.

In 20 minutes in my experience you barely enter samadhi.

Katsuki says between exhalations is where samadhi lies. I agree. I noted waiting for about ten to 20 seconds, without undue difficulties, hastens the approach of samadhi or fana

Thinking also appears to disrupt this process of remaining 10 to 20 seconds between exhalations.