I played classic mode, which is maybe kind of stupid now the I notice your changes most probably relate to decay mode specifically. In my play through in this mode, however, I never took any damage as far as I could see (so not sure how this even works, it seems like it is ok to be on a black hole for a short time?), and I relatively quickly got to a point where no black holes were appearing at all. It would be better if I would take damage and die, in this first playthrough, and have to learn something in order to succeed. ;)