should i turn off my time machine during a mac os installation?

I do.

I make sure TM has a current backup before starting any upgrade. I turn TM off and leave it off until I can do some testing with the update. Then I turn it on again. I do this with Security Updates as well. Those have been troublesome for some users.

Another tip: I now note dates/times of updates in the Calendar app. If an update starts acting badly a few days after installation, it is easy to find exactly how far back to look in Time Machine for pre-install version to restore.

I would, not sure it matters but I still would. :)

Ok, take care my friend. :)

I've never turned it off. Never experienced any problems.