Templates are useful when the problem is mostly presentation. They become limiting when the website is expected to behave like part of the business.
The clues are usually operational
- Different user types need different experiences
- Data has to move between the website and another system
- Products or resources need custom filtering
- Editors need structured content rather than a blank page
- The site has authentication, workflows or compliance requirements
That is the point where custom development stops being decoration and starts becoming the product.
Build around the job
The useful question is not “which template looks closest?” It is “what does this website need to do, who needs to manage it, and what does it need to connect to?” The visual layer follows from those answers.