Consistency of using NOT NULL constraints on Boolean base table columns

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SELECT Count(*) AS nr_of_Boolean_cols,
Count(*) FILTER (WHERE is_nullable='NO') AS nr_of_mandatory_Boolean_cols,
Count(*) FILTER (WHERE is_nullable='YES') AS nr_of_optional_Boolean_cols,
CASE WHEN Count(*)=0 THEN NULL ELSE Round((Count(*) FILTER (WHERE is_nullable='YES')*100)/ Count(*),1) END AS percentage_of_optional_Boolean_cols
FROM information_schema.columns A INNER JOIN information_schema.tables T USING (table_schema, table_name)
INNER JOIN information_schema.schemata S ON A.table_schema=S.schema_name
WHERE A.data_type='boolean' 
AND T.table_type='BASE TABLE'
AND (A.table_schema = 'public'
OR S.schema_owner<>'postgres');