Moving parts (other than RRoD) are the major reason for failure. HDs are among the worst offenders. The PS3 has a full SATA compatible drive slot and easy data transfer instructions. Designed to be owner accessible. Mine has a SSD now. Not so much on the 360 part, and my Jasper’s (hw rev) hard drive is not sounding great. There are utils for emulating the insane drive ID and custom boot block but why am I required to jump through such hoops.
Oh yeah, when I picked up my 360 and Ps3 recently, just judging by the time frames of the models and how little save games were on it - they didn't have a hard life.
My Ps3 only had save games for a WWE game and GTA 5 from 8 years ago. I figured if I could get 2 years out of these things that would be more than I could ask for. Storing these so the HDD's are stacked sideways can also help prevent head crashes. But that plan looks more like urban legend hyper mileing than anything that will make these last. Maybe it will buy a few months but then it puts more stain of the DVD/Bluray drives.
An SSD for the Ps3 will be the next step. The 360 because it is the E model actually has a reasonable solution. It has a 4GB internal storage that takes over if the HDD is removed. Then you can just store games on an external USB drive. It isn't amazing but it would work. I just worry about these things over heating because even the series E's would red ring with enough time.