I'm curious as to how long you keep your MBP before upgrading to a new laptop. I have a 2011 MBP, seriously considering a new rMBP. Just checking the forums today, at least two people on page 1 upgraded their 2011 MBP to a 2015 rMBP. Is 4 years the standard upgrade cycle? Or is it just selection bias speaking? I will make my final upgrade decision myself, so no advice needed here. But I was just curious. Do you take 2 years? 4? More, less?