Identify When to Use Backer Rod for Gaps

is there times when I just don't need to use that garage so I'll typically tell folks that I start thinking about using background when the joint's about a half inch or deeper anything from a quarter to 3 8 you you really don't have this problem right where you're getting too thick right right to the point where it's not going to move anymore um but yeah it comes in a bunch of different sizes I mean I'm looking at