Is it needed to set the slices for MOLAP

Is it needed to set the slices for MOLAP? For SQL2008R2? Most of the related blogs are about 2000/2005. My tests shows it works fine without slice. SQLCat says 'Cube partitions each have a slice for each attribute. This slice is either set by the administrator as part of the partition definition, or for MOLAP partitions is created during creation of the bitmap index for the partition.' And in 'Analysis Services Performance Guide SQL server 2008, October 2008' you can find: 'For MOLAP partitions, during processing Analysis Services internally identifies the range of data that is contained in each partition by using the Min and Max DataIDs of each attribute to calculate the range of data that is contained in the partition. The data range for each attribute is then combined to create the slice definition for the partition. Knowing this information, the storage engine can optimize which partitions it scans during querying by only choosing those partitions that are relevant to the query.'