As others have said, all you need to do is pull the SD card and update it from a PC/laptop if you want to leave the 740 in the plane. You can also go old-school and create an update package on a USB thumb drive and again do your update in the plane, though that method will take longer.
However, round-barrel power connectors were designed for easy unplugging/plugging, and millions of devices have been using various iterations of such connectors for years, with jillions of cycles and low failure rates. With normal use, there will be no problems. SD card and USB ports are also designed for frequent usage and long cycle lives. The antenna connectors are a little more delicate and not as common, so I don't know about those...but do you really need an external antenna? My 720 gets great GPS reception just from its built-in receiver, though nowadays I feed it with a Stratux and so the internal GPS is not used.
There are lots of things to stay up nights worrying about. Wearing out your 740b because you take it home after every flight is not one of them.
I take mine home after every flight just because I prefer to have it with me instead of sitting in the plane.