INCREMENTAL Statistics taking long time

Hi Guys

I have table, lets say ACCOUNTING_DIRECTION, which has roughly four hundred sub-partitions per day. The table holds data since 2015. There is roughly forty-six thousand sub-partitions. They are all BASIC compressed and the statistics are all up to date.

I have locked all table partitions older than a month using DBMS_STATS.lock_partition_stats('SCOTT', 'ACCOUNTING_DIRECTION', PARTITION_NAME), which leaves 6000 sub-partitions. 

The table preference for the table ACCOUNTING_DIRECTION, is INCREMENTAL=TRUE, METHOD_OPT=FOR ALL COLUMNS SIZE 1, CASCADE=TRUE, GRANULARITY=AUTO AND STALE_PERCENT = 10%.The size of the table is 106GB. This table is regularly inserted through out the day.