I only write tests in two situations: 1) mission critical parts of my system that will cause damage if they break 2) small functions that I can't wrap my head

I only write tests in two situations: 1) mission critical parts of my system that will cause damage if they break 2) small functions that I can't wrap my head around (eg some complex regex extraction) Everything else can be fixed fast with minimal damage as it comes up. My test coverage is less than 1%.