Define moderation. In general, it's a good idea; things that are bad for you can't do much damage if you are only exposed to a little, & things that are good for you can cause problems if you get too much. Finding the right balance is an ongoing battle, one we all face every day. Good luck, & i hope your balance is good!
Not everything! Poison cannot be taken in moderation. But for most things it's a helpful guide.