The T-35, sometimes called the "land-battleship" is one of the only heavy multi-turreted tanks that saw actual use in the war after 1940. Unfortunately, I can't find any accounts of its effectiveness aside from its terrible technical deficiencies, which apparently caused losses of up to 90% due to mechanical failure. When it did manage to make it to a fight, how did the t-35 do?
In general, very poorly. With so many turrets, crew coordination was a major issue. Mechanical failures plagued the tanks. They were too heavy, breaking bridges or getting bogged at the worst moments.
u/TankArchives has compiled a list of the fate of some of the last T-35s.
If you're interested in the T-35 check out Francis Pulham's Fallen Giants: The Combat Debut of the T-35A Tank. If you don't wanna drop $10-20 bucks on the book, this interview with Pulham covers the gist of it.