After letting those tangled thoughts sit in my head, I came up with a better conclusion.

1.) It depends on the genre too.

Actually, I really enjoy sad music or sad novels too. But when I think about repeating such themes, it depends on how much sadness I’ve experienced.

If it’s too overwhelming, just once is enough.

If it’s only mild sadness, maybe I’ll give it a second chance.

But for me, I write non-fiction, so it’s nearly impossible to make readers feel bad if I want them to keep reading.

2.) Emotion is a spectrum.

I really hate "toxic positivity" too. I believe we’re human and that experiencing sadness is healthy if we use it in the right way.

So, I think mixing and matching emotions plays a crucial role here.