WP_POST_REVISIONS is a constant, so it applies to the whole site. A catalogue whose products are updated by a nightly import does not want a revision per product per night, but the blog on the same install probably does.
add_filter( 'wp_revisions_to_keep', function ( $num, $post ) {
return 'product' === $post->post_type ? 0 : $num;
}, 10, 2 );The filter receives the post, so the decision can be per type, per author or per anything else. Existing revisions are not removed by this — they need a one-off cleanup, and on a site that has been importing for a year wp_posts is frequently more revision than post. Deleting them is also the fastest way to shrink a database that has stopped fitting in the buffer pool.