Any way you slice it, cross-posting is a bad idea (with a few exceptions)
If you have the same followers on more than one social media platform (and most of us do), auto-cross posting can look like spam. Too much of it and there is no reason to follow you on each site. Or you could simply be ignored on each.
The opposite applies as well.
If you auto-cross post, you run the risk that none of your posts are seen or only seen once. Taking the time to spread out the postings provides a greater opportunity for them to get visibility and create multiple impressions.
Rather than a chance for that person who follows you on five sites to see the post 5 times, automatically generated posting significantly reduces that possibility. They cannot be in 5 places at once. Unless the post remains in the feed or they flip between sites.
Marketing 101 – it’s all about the impressions. It used to require at least 7 impressions before you could expect a return. That number, with all of the clutter, is now likely 3-4 times greater.
And if they do see the post multiple times?
Cross-posting ignores another basic fact.
If your post didn’t catch your reader’s attention the first time, what makes you think it will the second or third time? See it too often and the reader will start to tune it out. Think about how you respond when you are the reader.
Varying the content or the image, switching from image to link or link to video doesn’t change the message, only how it appears to the reader. The same post published 3 different ways with the same message increases potential reach AND engagement. It increases the likelihood of it resonating with your reader.