From Waterfall to Continuous Development: Key Points

The big problems with putting localization at the end of the development process, like in the waterfall approach, is a slower return on investment as you wait for everything to be localized before the product is released. It also ties you down to a certain set of code that cannot be altered or otherwise allow localization to influence the product development cycle.

On the other hand, when using an agile or continuous development methodology, localization happens in parallel with development. The advantage is that localization will have an influence on what happens in development, leading to a more quality localized product at release as well as a quicker release date.