Judging by one guy who left (or was fired, I don't know) while I was there, and several more from other departments then I think you are spot on -- they did seem to cast a wide net and just let some of the fish fall through. Guess it was easier that way?
I was painfully aware that I had to put in 12+ hour working days until I show a productive output, yep. But sadly the stars aligned against me: during the same period my wife had severe depressive episodes I had to help her through, my mother almost died and me and my wife took turns "patrolling" the hospital where she was laying for days, had a huge fall out with my brother during the same time, and I finally cracked under financial and emotional pressure (not going to bore you with my life story but let's just say that the last several drops made the cup overflow). On top of that I was asked to comply with weird culture and practices that put extra pressure on me.
So I wasn't able to do what I was very keenly aware that I should do to keep the job. I am still a bit sad about it because I know for a fact that the whole thing actually started taking shape and I found my motivation and energy and desire to work on the problems in detail and with good craftsmanship... but it was too late at that time, apparently.
I'm sorry that you feel like you have to give reasons why you weren't able to work 12 hours a day. That's an unreasonable, unhealthy, and frankly disrespectful expectation from your employer whether it's explicit or hidden. I'd encourage you not to try to justify or excuse it. I can't imagine that losing the job is easy, but
it's not your fault
that you were subjected to that, or that you did not match their terrible standards.
I was painfully aware that I had to put in 12+ hour working days until I show a productive output, yep. But sadly the stars aligned against me: during the same period my wife had severe depressive episodes I had to help her through, my mother almost died and me and my wife took turns "patrolling" the hospital where she was laying for days, had a huge fall out with my brother during the same time, and I finally cracked under financial and emotional pressure (not going to bore you with my life story but let's just say that the last several drops made the cup overflow). On top of that I was asked to comply with weird culture and practices that put extra pressure on me.
So I wasn't able to do what I was very keenly aware that I should do to keep the job. I am still a bit sad about it because I know for a fact that the whole thing actually started taking shape and I found my motivation and energy and desire to work on the problems in detail and with good craftsmanship... but it was too late at that time, apparently.