A system for providing content to a plurality of client devices, comprising a computing device comprising a processor and a memory device, the processor executing a classifier, the classifier configured to: receive an indication of a first content stream transmitted to the plurality of client devices, the first content stream comprising a content item and a secondary content item slot; receive an array comprising durations of a plurality of previous secondary content item slots associated with the content stream; determine for the first content stream, a plurality of classes, each of the plurality of classes associated with a different time duration of a corresponding plurality of time durations; determine a number of the plurality of client devices concurrently receiving the content stream; if the determined number of the plurality of client devices is above a predetermined threshold: classify the secondary content item slot of the first content stream into a first class of the plurality of classes based on the array comprising the durations of the plurality of previous secondary content item slots associated with the content stream; and retrieve, based on a time duration of the first class of the plurality of classes into which the secondary content item slot was classified, a different secondary content item for each of the plurality of client devices to display during the secondary content item slot of the first content stream; if the determined number of the plurality of client devices is below the predetermined threshold: wait for receipt of an indication of the duration of the length of the secondary content item slot for the secondary content item, the indication being included in the content stream a predetermined amount of time before the start of the secondary content slot; and select a second content item to place into the secondary content item slot of the first content stream responsive to the indication of the duration of the length of the secondary content item slot for the secondary content item. receive an indication of a first content stream transmitted to the plurality of client devices, the first content stream comprising a content item and a secondary content item slot; receive an array comprising durations of a plurality of previous secondary content item slots associated with the content stream; determine for the first content stream, a plurality of classes, each of the plurality of classes associated with a different time duration of a corresponding plurality of time durations; determine a number of the plurality of client devices concurrently receiving the content stream; if the determined number of the plurality of client devices is above a predetermined threshold: classify the secondary content item slot of the first content stream into a first class of the plurality of classes based on the array comprising the durations of the plurality of previous secondary content item slots associated with the content stream; and retrieve, based on a time duration of the first class of the plurality of classes into which the secondary content item slot was classified, a different secondary content item for each of the plurality of client devices to display during the secondary content item slot of the first content stream; classify the secondary content item slot of the first content stream into a first class of the plurality of classes based on the array comprising the durations of the plurality of previous secondary content item slots associated with the content stream; and retrieve, based on a time duration of the first class of the plurality of classes into which the secondary content item slot was classified, a different secondary content item for each of the plurality of client devices to display during the secondary content item slot of the first content stream; if the determined number of the plurality of client devices is below the predetermined threshold: wait for receipt of an indication of the duration of the length of the secondary content item slot for the secondary content item, the indication being included in the content stream a predetermined amount of time before the start of the secondary content slot; and select a second content item to place into the secondary content item slot of the first content stream responsive to the indication of the duration of the length of the secondary content item slot for the secondary content item. wait for receipt of an indication of the duration of the length of the secondary content item slot for the secondary content item, the indication being included in the content stream a predetermined amount of time before the start of the secondary content slot; and select a second content item to place into the secondary content item slot of the first content stream responsive to the indication of the duration of the length of the secondary content item slot for the secondary content item.