log shipping with pg_receivewal

if I setup pg_receivewal from a primary instance to a given directory, and then setup a standby with a restore_command pointing to that directory,, the changes on the primary are applied on the standby at each wal change. And this, even if I run pg_receivewal with the --synchronous option.

My question: as the synchronous option is supposed to make pg_receivewal write transaction immediately in the wal files, is there a way to ask the standby to apply them on the fly ie. without waiting a wal file change ?

thanks,