The problem with the electronics side of the cameras is that it can be very hard to determine how long they will last. The Silicon and Gallium based components do not seem to have a normally distributed failure rate. They have a significant spike of early failure, which accounts for those DoA units, and the ones that fail soon thereafter. After this there is a relatively low steady rate of failure over a very long time period, which will, I assume, eventually be followed by some sort of roughly normal type period of failure. The biggest issue with this is that this failure bell curve is very wide, so wide in fact that it makes the SD such that the mean is a pretty useless indicator. That is for the transistor based components. What are far more likely to fail are the electrolytic capacitors. The problem with electrolytics is that they do not like being left without charge for extended periods of time, and they are usually used in the power regulation circuits. If you only use the camera occasionally, say for you annual summer holiday, you will put it away fine, and then when you get it out the following year it will be dead when you try to turn it on. This is the typical mode of failure of an electrolytic capacitor. So these capacitors tend to have a failure mode that is based on not using the device, unlike just about any other component in there. Other than the electrolytic capacitors what IMO kills most electronics is electrical and thermal shock. So the best thing you can do for that is very often just keep the system permanently powered up. That way you do not have the system having to keep warming the system back up to working temperature, or the electrical effects that happen during power up. Given that cameras are battery powered, leaving them permanently on is not really practicable, but I would still try to use it at least every couple of weeks at the minimum.
Please note that I have not gone away and actually looked any of this up for facts, it is based just on my personal experience. I did though serve in the RAF for nine years as a radar tech, and then went on to do a degree in electronic engineering. So hopefully my experience and knowledge is relevant to the subject.