Optimal Redo log size

Hi all,

DB version is 11.2.0.2 three node RAC. fast_start_mttr_target is set to 300.  The value optimal_logfile_size gives us below

SQL> select OPTIMAL_LOGFILE_SIZE from v$instance_recovery;

OPTIMAL_LOGFILE_SIZE
--------------------
                3976

1 row selected.

Currently 18 redo logs of size 250MB each is there in the database.  Is that good to increase the size as mentioned ??

Thank you,

baskar.l