We have four different kinds of "review boards" so the answers to your questions will vary depending upon what type it is.
The Cadet Candidate Evaluation Board (CCEB) conducts the initial review of applications and is constantly reading from October to April...they review hundreds of applications per week. Admissions Committee, the board reviewing all records recommended for direct appointment consideration by the CCEB, meets every other week from October to April...they review however many records have been recommended for direct appointment consideration since the last board met. The Coast Guard Academy Scholars (CGAS) Program review board is essentially also constantly reading from October to April...they review however many records are being recommended for CGAS appointment consideration by the CCEB. Finally, the Wait List review board meets as convened by the Director of Admissions, usually once or twice during the month of May and once in early June, and will review all applicants who have accepted their spot on the wait list.