When I make a journey I know it is only a CEV, a sub break through or a break through.

Is it possible that a sub break through after a while changes into a break through and than again back into a sub break through? Or is this 'technically' impossible?

Do you folks have experienced this?

The general consensus is that you are definitely able to tell when you have broken through and when you haven't. There is no blurry dividing line, it is quite sharp and distinct. What can occur though is that it may take less DMT to put you over that line and somehow your sub-breakthrough dose becomes a breakthrough. This is known as reverse tolerance and is caused by the pathways DMT previously created being re-activated, it is presumably responsible for why people wake up in the middle of the night with the feeling like they are tripping on DMT because serotonin is linked to sleep and DMT acts on the serotonin receptor, making the firing of the receptor engage the previously activated DMT pathways.