In most cases, separate validation functions for each field type are the better choice. This approach aligns with the Single Responsibility Principle (SRP) and makes your code more modular, readable, and maintainable. It also simplifies testing and debugging, as each function is responsible for a single task.

However, if your validation logic is very simple and unlikely to change, a single function with a switch or if-else structure might suffice. Just be cautious about maintaining clarity and avoiding overly complex logic.