Is wp_reset_postdata always necessary?

Question

After run a query

$posts = (array)new WP_Query($args);

I use this data to do some calculation on post meta. I didn't display the posts. Do I still need to use wp_reset_postdata after the query?

Answer 1

If you called the_post() on the query, then yes. This resets the global variables used in the main queries.