The duration varies depending on the app's complexity and scope. A simple app might take 4-8 weeks, while a more complex project could take 3-6months. The timeline includes research, UX/UI design, testing, and revisions.

I design responsively, creating flexible layouts that adapt to various screen sizes. I use techniques like fluid grids, flexible images, and media queries. I also test designs on multiple devices to ensure consistency and functionality across platforms.

The handoff includes detailed design specifications, asset files, and a comprehensive design system document. I provide annotated designs explaining interactions and behaviors. I also remain available to clarify any questions during the development phase to ensure accurate implementation.

I have regular check-ins and presentations at key milestones. After each major phase (research, wireframing, visual design), I present our work and gather feedback. I then iterate based on this input. I also use collaborative tools that allow for ongoing communication and quick feedback on specific design elements.

I conduct several types of usability testing: Early-stage testing with wireframes or low-fidelity prototypes to validate user flows and information architecture. Mid-stage testing with interactive prototypes to refine interactions and features. Late-stage testing with high-fidelity designs to fine-tune the user experience and catch any remaining issues. I use methods like user interviews, task analysis, and A/B testing. The goal is to identify and resolve usability issues early and ensure the final product meets user needs and expectations.