However, I wonder if google considers the nature of time site as well?
I guess it depends on the situations. I can tell you when my PR was all over the medias (thousands of link), my site wasn't penalized. On this kind of work, I am looking for traffic, not links building.
Why would they treat it as spam? If you are posting quality and informative content, the bots would be more than willing and happy to come and index your site. I don't think there's any issue with posting too often.