one trigger for multiple tables
There is no option like that.  A trigger belongs to a table and that is that.  However, if all your triggers use the same procedure, you can easily generate a nice text output with all the CREATE TRIGGER statements.  The only thing to do is to collect the desired table names and then prepend and appent the necessary parts to those.

You can get all table names from a given schema with a query like this:

SELECT p.tablename
FROM pg_tables p
WHERE p.schemaname = 'public'
;


If now you select 

'CREATE TRIGGER tuweke 
AFTER INSERT ON ' || p.tablename || '
FOR EACH ROW EXECUTE PROCEDURE tuwekeAdjustextract();
'


instead of p.tablename then you are ready.  Copy the output and run it.