You've been told that you should frequently post to your blogs. But if you don't have time to log in everyday and post to your blog, and you should not post a bunch of blogs for the same day, you can write a bunch of blogs and schedule them to spread out over a number of days.
The reason you should not post a bulk of posts for one day is that Google (and maybe other engines) will penalize you if you do that. So you need to spread them out. But that doesn't mean that you can't write a whole bunch and then schedule them.