[Closed] Why use WPML and not classic way of translation?

Background of the issue:
I am working on a site using Themify Builder and WPML. My client is questioning the necessity of using WPML for translations. They were surprised that the design needs to be completed before implementing translations due to the need for design changes on each translation. I am considering whether to use Advanced Translations or to duplicate and translate each page independently.

Symptoms:
The client finds it wasteful that design changes need to be made on all translations of the page.

Questions:
Why do I need to use WPML instead of the classic way of translation?
Can I use Advanced Translations with Themify Builder?
Should I proceed with duplicating and translating each page independently?
Is there a more efficient way to handle translations with WPML?