I can't really picture what you mean but if you're talking about sticking thick trim x 3 on a small cut then no, use something that doesn't look so harsh like Silicon.
Generally you want to learn the art of siliconing because it can really make a standard job look rubbish-hot, and for areas such as your kitchen sink you'd automatically be thinking 'i'll get the gun out on this bit'.
If you're talking about tile trim then yes, you'll need to finish those edges off.