Can a substitute enter the game between quarters and during time-outs without being beckoned by an official?

A substitute entering the game between quarters and during time-outs is indeed allowed without needing to be beckoned by an official. The rules establish that during those specific instances, players can enter freely as the game is not actively in play. This provision helps streamline the flow of the game, allowing for adjustments in strategy or personnel without interrupting the natural rhythm of play.

During time-outs and between quarters, the game is paused, which means there's no play in progress, and the officials are not actively managing the on-court flow. Thus, players can enter or exit the game at those times to prepare for the next phase of play. This facilitates smoother transitions and allows teams to adapt to changing situations without unnecessary delays.