About -Wall option

Hi, I have a question, what's the best way to program? - put all the signatures in the Haskell Code? - Only put the type signatures needed to compile (like monomorphism errors or ambiguous signature)? Until now, I prefer the second one, but when I use the -Wall option, there's a lot of complains about type signature. Maybe the type signature is something that not need to be checked as a warning. But if the best practice is to put all the signatures, I found that Cabal generated code need to be fixed, because -Wall complains about it also. -- Thanks, Luis Cabellos,