Two things should be built in from the start, not added later. The first is phone use. The layout should be planned for small screens first, with buttons big enough to tap and a call option that's easy to find. Our Responsive & Mobile Website Design page goes deeper on that. The second is access for people with disabilities, such as readable contrast, clear labels on forms, and pages that work with a keyboard. That's covered on our Website Accessibility Design (ADA) page.
Not every project needs every step at full size. A small update to one page might only need a quick look at the data, a revised wireframe, and a test. A full redesign needs all of it. Scope is the biggest thing that drives cost, so ask any provider which steps they're including and why.
When the project ends, you should walk away owning the design files, the prototype, the style guide, and full access to your analytics. If a provider keeps those, you're tied to them for every future change. Ask about this before you sign.
UI/UX work sits right between design and code. Our founder worked as a software engineer before building websites, which is why this work is handled the way a software company would handle it, with the build in mind from the very first sketch, so the design you approve is one that can be made to work.
That same focus carries through the practical software company guidance our team provides to local families.