No Idea. Probably not too long contrary to what others will have to you believe.
Strange, there were 2 updates during April of this year alone. Not to mention I have 13 different versions of devkit update zip files dating back only to the 26th of December 2015 alone. (I would have more but my hard drive died around that time and I lost my downloads folder) That’s quite a bit less than 3 months since the last release and if you average it out that’s a little more than 2 releases a month. I would hardly call that “Few and far between”.
I’ll admit there are some issues but not even close to what you’re describing.
I don’t know why people insist on exaggerating and spreading misleading information on things like this so much. Please stop.
Thank you.