The lawyer has the job of assessing the evidence and advising the client on the basis of that and the client's instructions. They cannot ethically advise a client on how to plead. That must be fully the client's decision. They can explain the consequences of a guilty plea. For murder there is no sentencing discount in Qld so often an accused will just roll the dice and see if the Crown evidence all comes up to scratch. On occasion, cross examination will castr doubt on the strength or reliability of the evidence of a witness. Sometimes errors will be uncovered in the way forensic evidence has been dealt with or intepreted. If there is a guilty plea to murder then the circumstances are not likely to be discussed in any depth at sentencing. The penalty is pre-set and the Crown will not have tendered its evidence as to the circumstances at trial.
If there is a plea of guilty to manslaughter then there can be a sentencing discount. To be of any signficiant quantum though, it needs to come fairly early on as the discount is largely for saving the time, expense and trauma of a trial, not for any show of remorse or contrition of the offender. Those latter things can be a separate mitigating factor. All IMO.
