The “maximum timespan of the Gandhabba state” is the duration of the human existence for a given lifestream.
– In Brahma and Deva realms, that Brahma or Deva is born just one time for the duration of that existence.
– But in human and animal realms, the “mental body” (or the “gandhabba body”) lasts for the whole duration of the human or animal existence. That time is NOT a fixed time period. It could be many hundreds of years to many thousands of years. During that time, one may be born with a human body many times. In between those births with physical bodies, one is in the “gandhabba state.”
So, the answer is that the “maximum timespan of the Gandhabba state” can be many thousands of years.
– That is why “this person saw ghosts from the Renaissance era while in a vacation to Venice” is possible. That is not a ghost, but just the “mental body” or gandhabba. It is human without a physical human body.
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