The question that begs an answer is, how can I improve this situation? One way to do that is to run a CLUSTER clause:

test=# h CLUSTER
Command:     CLUSTER
Description: cluster a table according to an index
Syntax:
CLUSTER [VERBOSE] table_name
[ USING index_name ] CLUSTER [VERBOSE]

The CLUSTER clause will rewrite the table in the same order as a (btree) index. If you are running an analytical workload, this can make sense. However, in an OLTP system, the CLUSTER clause might not be feasible because a table lock is required while the table is rewritten.