In one aspect, a method includes receiving from a content-presentation device a request for first supplemental content for presentation during first content-modification operation, and transmitting to the content-presentation device a link to a set of content items in a playlist including the first supplemental content. A request may be received from the content-presentation device for second supplemental content for presentation during a second content-modification operation. A determination may be made that the second content-modification operation is scheduled immediately after the first content-modification operation. Responsive to the determination, the playlist may be modified to include the second supplemental content positioned immediately after the first supplemental content. The link may be configured for retrieving the first and second supplemental content by the content-presentation device, and for performance of the first content-modification operation and the second content-modification operation immediately after performance of the first content-modification operation.