The outside review letters are very useful in providing a complete overview of scholarship. Sometimes seeking that security means that there is terrible insecurity beforehand and too much security thereafter. Input is solicited from department, dean, students, outsider reviewers. Members are chosen through a public process. Giving the faculty a strong voice in the making of promotion and tenure decisions, one which is awkward for individual administrators to overrule.
Feedback starts early and comes often.
Whether you are performing well or poorly, you are kept informed of any problems that may arise in your candidacy. Your department has a relatively strong say in the matter, yet the CPT contributes uniformity across the institution. The timeframe for these reviews is reasonable. The process is largely under the control of the candidate. For the most part, the candidate has some options as to what gets included in a review and what doesn't.