Sorry, actually is 3 shards and 1 replica.
the problem i'm trying to solve is the cluster recovery time, with 2000 indices and around 13k shards takes between 1h to 3 hours to recover... and bigger indices are the ones that take longer.
by breaking those big indexes in 4 smaller shards, i hope that ES will recover then faster, as at least 3 of then didn't change and full recovering the last one would be faster as it is much smaller