Personally, in the last 5 years of blogging every single day of posting was not necessary. I experimented a few times with doing it and found no really positive changes to speak of.
There are some big names who do write a post everyday.
But for as many that do ,I can find other really big successful Bloggers who do not post everyday. (Sometimes just once a week)
I think some follow the latter because they have tried and found their material stale and
rehashed ;consequently this turned many of their readers off !
And I think the important thing is to maintain some kind of consistency to keep your Readers engaged and informed.
If that means twice a week or once a month then so be it.
Just let your readers know what to expect.
However, I must admit that once a month posting on a blog is stretching things a little far. You might find that your Readers will begin to dissipate after such a wide gap in being active on your blog.
I am going out on a limb to say that you really need to post once a week, bare minimum. That is just me.
What do you guys think about posting and the frequency that many of you do on your Sites ?