What is the point?

I'm starting to wonder what the point is of Compassion's correspondence program.  I've had 2 correspondence kids since mid-September 2013, and I've received exactly 1 letter from each of them, despite writing every 3-5 weeks to them.  I've had my other 2 correspondence kids since the beginning of January, and I've only heard from one of them.  In 3 days, I will be putting in another inquiry on Juan, my Colombian correspondence child who I haven't heard from at all in 6 months.
I'm also at the point where I want to sponsor another child with another organization, but I feel as though I already have too many kids to write to.  There is a huge part of me that wants to drop all 4 of my correspondence kids through Compassion.  Let someone who has more time write to them, and that frees up some of my letter writing time to sponsor another child.
But, I also think, why not just decrease the number of letters I write to my correspondence kids?  Do I really need to write to them monthly when it appears as though I'll be hearing from them 1 or 2 times a year?  Could I drop it to every other month, or the program's minimum requirement, which is 3 letters a year?
I do feel badly, because I willingly signed up for the correspondence program, having very fond memories of it from back in 2010.  Some of my correspondence kids were my best writers.  Now, it seems, as with all Compassion kids, letters are few and far between, but I still feel obligated to write regularly to them, and thus cannot take on another sponsorship at this time.