Check the allowance at the game boundary
Under the current video-review appendix, a best-of-five match reaching its fifth game gives each player one additional review, while unused earlier reviews do not carry into that game. Adding the unused balance to the new allowance would misread the procedure.
Imagine one player reaches the deciding game with an earlier review unused, while the other has exhausted theirs. Simply carrying the first player’s balance forward would produce unequal totals that the deciding-game provision does not describe.
Distinguish player reviews from referee referrals
An official seeking a video decision is a separate mechanism from a player spending one of their allotted reviews. A camera cut to a replay is not enough to establish that a player’s balance should fall.
Keep the initiating event in the viewing note: a player request or an official referral. Then check the game boundary before updating the allowance. This explains why a review graphic can reset or remain unchanged despite another video sequence being shown. It does not imply that every match has video review available or that every type of call can be challenged by a player. The article concerns the allowance when that system is in use.
Questions answered
Do unused earlier reviews simply accumulate into game five?
No.
Does every official video referral spend a player review?
No. The mechanisms are separate.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.