Consolidation for Incremental retention can be disabled in the Reflect Defaults and Settings:
If consolidation is disabled and Incremental retention is applied to a backup set, Incremental backups are only deleted if to do so will not break the backup chain.
The number of incremental backups retained will always be at least the number specified by the Incremental retention rule.
Example with Consolidation disabled:
Retain 3 Incremental backups
At this stage there are 7 Incremental backups and there have been no retention deletions so far as to do so would either break the backup chain dependencies, or leave less than 3 Incremental backups.
The next Incremental can safely delete Inc1 to Inc5, leaving 3 Incremental backups, Inc6 to Inc8
The backup log will indicate when consolidation is disabled and an Incremental merge is skipped: