I have the feeling that even a single capable software engineer from a bank (or any client) who is put into different teams of the contractor and reports back t

I have the feeling that even a single capable software engineer from a bank (or any client) who is put into different teams of the contractor and reports back to the client, would already make a big difference. Does not replace testing at all, but would at least inform the client about possible problems, so they can stop the whole project early enough.