One argument against saying "whatever works for you" is that it makes it appear that you don't have anything else important to do. This can lower your status, particularly with alpha male top gun types (VCs, I'm looking at you) whose minds naturally slot people into a pecking order. If you want a hierarchical-thinking person like this to respect you, you have to convey that you too are an important person with important things to do and other important people to see. So consider the context: say "whatever" to your friends but never say "whatever" to status-obsessed people you need to get money from.