Pros and cons of a single supermemo collection

There is no good and right about having one single collection or several for SuperMemo. You may decide when it is best to start a new collection, merge collections, or transfer branches between different collections according to many factors and current needs.

Interleaving

Video/audio repetitions break the flow

Stats

Averages may be not representative

Collection parameters

Same collection parameters for different difficulties

Priorities

Requires more precision for prioritization