Avoid Duplicate Code
When possible avoid duplicate code.
Duplicate code creates a larger code footprint to search through when trying to add new features are resolve bugs.
Duplicate code creates more workload for the PHP pre-compiler. This means it will consume more memory and processing time on every single PHP interaction.
Duplicate code consumes more space on disk, more space in the repositories, and in memory for processing.
Overall duplicate code makes the application less performant and more brittle.