I always have two tablets and carry them in separate cases most of the time. Both with the same music and both charged ready to go. Unfortunately they are the same model (I could not afford any other back then, but I will eventually have a newer one and take one of each kind. This way if there is an OS update it will probably only be done on one of them, etc.)
My main music tablet does not have many apps in it, basically it is solely devoted to gigs, and I have wireless off and manually turn it on for any updates, then off again.
I am not sure I would ever rely on only one tablet if it is as crucial as a concert. And I often take a box of the printed music in the car also.
I expect in a year or so the batteries might not hold charge, so taking the power or portable USB power supply would be essential soon.
Sometimes I just go with paper as I used to
My main music tablet does not have many apps in it, basically it is solely devoted to gigs, and I have wireless off and manually turn it on for any updates, then off again.
I am not sure I would ever rely on only one tablet if it is as crucial as a concert. And I often take a box of the printed music in the car also.
I expect in a year or so the batteries might not hold charge, so taking the power or portable USB power supply would be essential soon.
Sometimes I just go with paper as I used to