Is my use of "I guess" natural?

Hi teachers. Could you please tell me if my use of "I guess" is completely natural in the 9 examples.

Example 1:

A: Didn't you hear from him?

B: No, I guess he had other and more important things to do.

Example 2:

A: Are you busy all week?

B: Yes, but I guess I can find time to see you anyway.

Example 3:

A: Was that all you wanted to talk to me about?

B: No, I guess I was also curious to hear about your new boyfriend.

Example 4:

A: He's fine.

B: Have you talked to him lately?

A: No.

B: Then how do you know?

A: I guess I don't.

Example 5:

A: She says I'll get better. I just have to train harder.

B: I guess that's right.

Example 6:

A: Maybe you shouldn't be driving drunk next time.

B: I guess it's my own fault then. (my own fault that I crashed my car)

Example 7:

A: She's pretty annoying.

B: So I guess you don't miss her.

Example 8:

A: Could you please shut up?

B: I guess I can try.

Example 9:

A: She has started seeing a therapist.

B: Okay. I guess that's good.