Gut to studs? Drywall question

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Hi there, I am in a process of renovation of a house. The house is quite old, and has smell in it. The previous owner had pets. I will be changing plywood floor here and there. But I am more concerned about the drywall. I have popcorn ceiling everywhere and the drywall was covered with some kind of strange wood. I took the wood off already and the drywall is in a good shape. I wonder if I should or should not gut it to studs. I might be able to recover several rooms, but I am not sure about the smell and about the cost to finish this drywall. I would like to have level 5 finish, but the drywall was just taped and nothing more. Wouldn't it be cheaper just to take everything down and hang a new drywall?