I think b-sides and bonus tracks count since they were recorded in studio sessions and also cover EP's count.
You are probably right, but for the sake of this thread, maybe we should restrict the votes to studio albums.
In the past, there was no such thing as an EP until Alice in Chains made the EP popular in lieu of a full length album..........
Not all bonus tracks are studio recorded
Yes , Deep Purple,
Iron Maiden has recorded tons of covers. They put out a box set of mostly covers about 15 years ago.