UX designer should always emphasis on lean UX methodology as that is a do-able in any given situation.
Given that you will always find all the resources require to practice lean UX in your design studio or organization
He should always try to build the culture of practicing lean UX in his studio or organization. Which will help to to validate his experience that he has designed which will lead to ship a better product in very less time.
Lean UX is very essential for any organization for their growth strategies, it can give them cutting edge against their competitors.
Going with traditional process of user experience can b bit costly for early stage startups, but lean UX is something that they can adopt without any cost. Also traditional UX process can be time consuming compared to lean UX
Follow lean UX methodology and improve experience of your product by 10x (approx.) if followed in perfect pattern
Happy building experience!