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
Analytics
Duplicates
Backup
Time investment
Registries
Searches
Collection repairs
Collection parameters
Same collection parameters for different difficulties
Final Drill
Priorities
Requires more precision for prioritization