Hi,
I don't know if you're a consultant or an in-house developer.
One of the hardest skills to achieve as a consultant is being able to succesfully sell 'No!' to a customer. It is also one of the skills that makes a difference and where you can really see the added value of hiring a consultant/external party.
You can only get better in it by understanding the business requirements and the underlying needs and also challenging them when they seem counterproductive.
Kind regards, Rob Dielemans