If you think that time frame between posting your newly finished work is more helpful to you, then, as long as the output is consistent and reliable, it doesn't make a huge difference, so long as there aren't any frequent interruptions to the schedule.
People make a habit of reading comics at the usual time you make them, and subconsciously create an expectation that they will always get a new issue then and there. As long as you don't rock that expectation too much, it's no biggie.
Maybe finish this arc off like usual and then start that new output idea of yours next chapter, with an announcement with how you will publish these out come next time, yeh?
Remi-le-Oduen
The schedule is not that important to me, but I think that for general success and fanbase in social media more frequent posts are better, so I guess monthly, but longer have a risk of damaging your fanbase