Are period leggings actually useful?

I keep seeing ads for period leggings and I’m curious if they actually work or if it’s just good marketing.

Has anyone here tried them? Do they hold up on heavier days, or are they more for light flow/backup? And are they actually comfortable, or do they feel bulky?

I like the idea of something reusable, but I don’t want to spend the money if they don’t really do much. Would love to hear honest experiences.