Microsoft® SQL Server 2012 Unleashed

Automatic Checkpoints

By default, the frequency of automatic checkpoints is determined by the setting of the recovery interval for SQL Server. However, the determination of when to perform a checkpoint is based on the number of records in the log, not a specific period of time. The time interval between the occurrences of automatic checkpoints can be highly variable. If few modifications are made to the database, the time interval between automatic checkpoints could be quite long. Conversely, automatic checkpoints can occur quite frequently if the update activity on a database is high.

The recovery interval does not state how often automatic checkpoints should occur. The recovery interval is actually related to an estimate of the amount of time ...