The Red Hat Enterprise Linux operating system must be configured so that when passwords are changed the number of repeating consecutive characters must not be more than three characters.
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.
How this relates to the STIG checklist: STIG vs SCAP benchmark.