The review process mirrors the induction process. Where the induction process maps out their first week, month and quarter, the review process determines how the new recruit is progressing each week, month, quarter and beyond. The review process outlines where you want the new recruit to be at the end of each time period and measures how they are progressing against expectation.
Of course if you follow this process and the new recruit is falling short of your expectations you may decide not to keep them on after 90 days. One of our biggest mistakes that sales managers and business leaders make is not following an effective review process, resulting in the company-keeping people that they would rather let go. They either have no legal grounds for terminating their employment, or they have no real idea of where the new recruit should be at the end of the 90 days and must give them the benefit of the doubt.