The 1st Chabad Rebbe, Rabbi Shneur Zalman of Liadi, greatly praised the efforts of Rabbi Levi Yitzchak of Berditchev to find merit for each and every Jew.
He once said:[1]
“When a Jew recites Tehillim and mentions the Rav of Berditchev, the letters arrive in the “Hall of Merit’ and elicit mercy on himself and his household.”
[1] Sefer HaSichot, Summer 5700 Pg. 116