The focus on automated unit/integrations tests is a relatively modern thing (late 90's?). There was some pretty large and extremely reliable software shipped before that focus. Random example is that the Linux kernel didn't have much tests (I think these days there is more testing). Unix likely didn't have a lot of "tests". Compilers tended to have them. Operating systems less so. Games (e.g. I'm sure Doom) didn't tend to have tests.
You need to find a balance point.
I think we know that (some) automated tests (unit, integration, end to end) can help build quality software. We also know good tests aren't always easy to write, bad tests make for harder refactoring and flaky tests can suck a lot of time on large projects. At the same time it's always interesting to try different things and find out what works, especially for you if you're a solo developers.
You need to find a balance point.
I think we know that (some) automated tests (unit, integration, end to end) can help build quality software. We also know good tests aren't always easy to write, bad tests make for harder refactoring and flaky tests can suck a lot of time on large projects. At the same time it's always interesting to try different things and find out what works, especially for you if you're a solo developers.