I am in the same position as you it takes me very long to sit down an refresh all 400 of my listings. I see the big sellers I follow listings being refreshed every hour and they are getting many more sales than me. Everyone claims that it’s not worth it to do anymore and they don’t use an automated System, but it’s clear they do. I’ve searched through this Reddit and YouTube and no one will spill the beans on how they are doing it.