Maybe my english is bad, I will try to explain another way.
Let players be A, B, C, D, E, F. A is scum.
Example 1.
A: if I am SB i will check B.
B: if I am SB i will check C.
C: if I am SB i will check D.
D: if I am SB i will check E.
E: if I am SB i will check F.
F: if I am SB i will check A.
Night 1. A trying to recruit D and failed. Now he will shoot C next night.
Example 2.
A: if I am SB i will check F.
B: if I am SB i will check F.
C: if I am SB i will check D.
D: if I am SB i will check F.
E: if I am SB i will check D.
F: if I am SB i will check D.
Night 1. A trying to recruit D and failed. SB is C, E or F, guessing chance is 1/3. Bad idea to shoot.
Also. Most likely the persons in possible SB's visit list will not be recruited even if not protected. Will scum risk to recruid D if 3 players said they will check him as SB? Likely not.