Executing DBMS_STATS.GATHER statistic objects (daily, weekly, monthly, etc...) command?

Dear Support,

How oven i can execute the following commands for optimization purpose, in order gathering different types of statistic object (daily, weekly, monthly, etc...)?

-- exec dbms_stats.GATHER_FIXED_OBJECTS_STATS;
-- EXEC DBMS_STATS.GATHER_SCHEMA_STATS('SYS');
-- EXEC DBMS_STATS.GATHER_SCHEMA_STATS('SYSTEM');
-- exec dbms_stats.gather_dictionary_stats;

Another qutstion Q:

Can I also execute the following commands in order gathering SCHEMA owner statistic information, if yes how oven?

-- EXEC DBMS_STATS.GATHER_SCHEMA_STATS('DBSNMP');
-- EXEC DBMS_STATS.GATHER_SCHEMA_STATS('SYSMAN');
-- EXEC DBMS_STATS.GATHER_SCHEMA_STATS('MDSYS');