I just ordered 8 more on Monday. That'll put me at 12 in this system. I couldn't pass up 8GB of DDR3 1600 for 50 bucks. I OCCASIONALLY use up all 4 I have now, but I don't do a whole ton of actual work on this computer.
i7 6700K - Z170 - 16GiB DDR4 - GTX 980 Ti - 512GB SSD - 256GB SSD - 500GB SSD - 3TB HDD- 24" IPS - Win10 Pro x64
2015 13" rMBP El Capitan