What common mistake do developers make with Route middleware groups, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Route middleware groups, why does the mistake cause problems, and what is the safer approach? One recurring problem with route middleware groups is applying it without understanding the boundary it protects. Putting business-domain calculations into middleware just because middleware runs on every request. In addition, Related routes can share middleware by applying a group rather than repeating each middleware declaration. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.