What is it you have to retune, the TV when you switch to it or the box when you switch back?
What is prompting you to retune, lack of pictures or an advisory message? If the latter, you can usually ignore it and retune some time later as the changes are likely to be minor and could well be of no interest to you.
If it is lack of pictures then you have a signal problem which needs to be sorted out and you should not, in that circumstance, retune but find the cause.