>Everyone on the team is responsible for good user experience.
True
>The existence of a person who does nothing more than "UX" is a process smell.
Depends on what you call UX. My definition of the noun "UX designer":
1. Participates in Observational Research (Watches customers use your software) right along side the product owner and developers. Any one who makes software design decision should be apart of the regular feedback loop. This can even include sales people if they are making design and feature decisions. If this doesn't happen you build the wrong software wich is a really bad ROI. (Note if you are building software where you accurately represent the user, such as github.com, Then this research can be skipped.
1.b Mentors new hires (dev, po, qa, etc) on how to get the most out of most out of observation research. Answers questions with reasons based on facts and proven knowledge. It is the UX designers job to help everyone take his or her job. UX is the whole teams job.
2. Participate in research debriefing with the rest of the team.
2.b Mentor new hires, and all I said above. UX is the whole teams job.
3. Use the "scenarios", "personas" and "activities" distilled from the debriefing to create a story map with the whole team (Dev, Po, QA, etc). From this story map "User Stories" and tasks are created.
3.b Mentor... and so on as said above.
4. Guide developers and mentor developers interested in making wire proto types to usability test.
5. Participate in Usability testing of said wireframes workflows.
5.b you know the drill, same as above.
6. Debrief on the results of usability testing.
6.b same as above...
7. Iterate on wireframes if necessary.
7.b same as above... (whole team involved, UX designer is mentoring, her job is to teach the team to make her job unnecessary.
8. By now hopefully we have spent very little man hours in finding a great solution to our goal. So we can code. Developers code and UX designer pair designs with them.
9. Team usability tests the product they just created.
9.b Same as above, mentors, etc
10. Debrief on usability test
10.b ...
11. Iterate on design, pair design with devs. Getting small details like padding and animation speeds right. With the goal of teaching the devs to the point that they can take the UX designers job.
12. Usability test again
12.b ...
13. debrief
13.b ...
14. Team releases product if its working for users.
15. Surveys and observational research to find out how effective is the "out put" (what we built) at creating "outcome" & "impact" (user time savings, user delight, increase in sales, brand loyalty, etc).
17. Debriefing on the Observational research, surveys, and quantitative data. Looking for things we could have done better. What worked well, what didn't, etc.
17.b ...
Note: the teams goal is not to maximize "out put". Many teams don't realize this. The teams goal is to _Minimize_ "out put" and maximize "outcome" & "Impact".