I don't do safety critical software myself but I work at a medical device company so I see the teams that work on patient facing products. Their cycles are much longer, management doesn't force new enterprise systems on them, they are very deliberate with changes. It's just a different paradigm. I didn't want to belittle the NASA guys but I just don't see much to learn from there. Their approach has the benefit of high quality with the trade off of slow pace of change.