Design Considerations For Horizontal Scaling

Okay. So, I have this monolith travel app I made a few months ago. It is the first Laravel app I made. As in, it's tightly coupled. Suppose I wanted to deploy this application. Would it be worth going through the haste of decoupling that application so it can scale horizontally?

In my later projects, I design them with DDD principles. Usually, I’d write a library that contains the main logic of my application (the domain layer) without a framework, writing specific interfaces for tasks that need to be delegated to larval or whatever I’m using (the Application Service Layer). Then, on Laravel, I implement the framework specific part (Architecture layer) like data persistence, logging, etc... And when designing like this, I can more easily prepare for horizontal scaling.

With this old app, however, all the logic are in the controllers.

Any advice?