Does it make sense to cross post to most than one community to read the most people and contribute to Lemmy being active or is that spam?

I used to just post on .world but disagree with some of their admin and mod policies so I try to post on .ml then cross post. Is it worth cross posting to even small instances or should I expect their users are on the bigger communities too? I don’t want to spam but only posting in .world misses the point of decentralization