If my boss posts something I will assume they found value in it and thinks it is worth the time of X people to read it for information. If they have a question about it, they will ask.
If reading it right now matters, they will say so.
If they are just trawling for likes and noticing who posts something first, I will find a new boss.
I ignore stuff our CEO posts all the time. there isn't a pretense that everything he shares is a big deal, and if it is something important he'll send in an email or mark it as such.
might just be our culture though, there's aren't really any "jockeying for position" situations.
If they are just trawling for likes and noticing who posts something first, I will find a new boss.