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 4790K - Z97 - 16GiB DDR3 - GTX 980 Ti - 256GB SSD - 500GB SSD - 3TB HDD- 24" IPS - Win10 Pro x64
2015 13" rMBP