Question
I've been trying to see if I have to wait a few minutes or a few hours before I continue posting to other groups.
I know for sure that if I copy-paste too quickly the same post in groups I get a temporary block.
I would like to share my posts with a lot of groups at once, rather than doing this.
Answer
The mere fact that you are contemplating this question should ring loud alarm bells telling you something.
Find a better way to market. An ethical, effective way.
What you're doing now isn't it.