in collection check vs extra index keys check, we’re not consistent about whether we overlap the end of a batch vs the start of the next batch. In collection check we might split up batches like {{

{start: minKey, end: 0}

, {start: 0, end: 1}, {start: 1, end: maxKey}}} whereas in extra index keys check it would be like {{

{start: minKey, end: 0}

, {start: 1, end: 1}, {start:2, end: maxKey}.}} Essentially collection check expects end and start to overlap, whereas extra index keys check expects them to not overlap. We should see if we can standardize this.