Free Friday - Joint promos on KDP Select?

Hi, all!

I'm curious how many of us have work in the KDP Select program? As many of you know (but some may not), part of the point of KDP Select is increased visibility on Amazon's platform through increased sales ranking and appearing on various genre bestseller lists and in 'also bought' recommendations.

After my first free promo, I noticed that my 'also bought' pairings were a useless hodgepodge of whatever else was free at the time, such as cookbooks and "How to Live a $100,00 Lifestyle on $20,000 a Year." One way to combat this is to put two or three of your books on promo at the same time.

A possibly more helpful way is for all of us to plan our promos together. If we were to pick the same day (or two days) and all go free together, then we'd be able to benefit from shared promotion (we all have blogs, FB and Twitter, right?), and our also-boughts would at least be in the same genre.

If we did this for May, I would suggest May 16 - 17, or May 30 - 31. This would give us a bit of time to notify the appropriate websites, get some blog posts up, etc. I've read that since ebook purchases are highest on Fri-Sat-Sun, that Weds/Thurs promos make sense so you get the boost going into the high sales period. I'm also skipping the Weds/Thurs going into Memorial Day as ebook buyers might be too busy BBQing that weekend to buy much. (If anyone has sales data suggesting that Memorial Day is primo selling time, please correct me.)

If we did this regularly, maybe once a month or once every other month, we might get some decent visibility for a shared indie event. Maybe pick something like the third Friday of each month and make it "Free Friday," Indie Summer or somesuch. (Yes, I know I said Weds/Thurs in one place and Friday just now, but I'm asking for input here, not trying to make the rules. )

What say you, good people?