Get latest 3 posts from multiple CPT in one query

This method uses a counter and 1 query. Only 3 posts from each post type can ever be displayed.

$args = array(
        'post_type' =>  array( 'type1', 'type2', 'type3' ),
        'posts_per_page'    =>  -1
        );

    $myquery = new WP_Query( $args );
        $type1 = 0; $type2 = 0; $type3 = 0; $count = 0;
        while ( $myquery->have_posts() ) : $myquery->the_post();

            if ( $post->post_type == 'type1' ) $type1++; 
            if ( $post->post_type == 'type1' && $type1 > 3 ) continue;

            if ( $post->post_type == 'type2' ) $type2++; 
            if ( $post->post_type == 'type2' && $type2 > 3 ) continue;

            if ( $post->post_type == 'type3' ) $type3++; 
            if ( $post->post_type == 'type3' && $type3 > 3 ) continue;

            $count++; if ( $count > 9 ) continue;

            // Do Stuff

            endwhile;

This might not be the best solution if you have a really large amount of posts because it will loop through all the posts and if the count is higher than 3 for the given post type it will go back to the beginning of the loop.