The phrase "a case of picking" is correct and usable in written English.
It can be used in contexts where you are discussing a specific instance or situation involving selection or choice.
Example: "In this project, we encountered a case of picking the right materials for construction, which significantly impacted the overall quality."
Alternatives: "an instance of selection" or "a situation of choosing".
It is not a case of picking a famous university.
It's just a case of picking a new game idea.
That said, for Lewis, it's not simply a case of picking a film and crowbarring it in.
And it's not just a case of picking between subject areas – you'll need to decide what type of qualifications you want to sit and whether it's best for you to do them at school or a college.
The longer F1 lift offers a variety of easier descents, while the shorter and steeper F2 lift takes adventurous skiers and boarders to the fell top, from where it is a case of picking a route to the bottom.
(If you believe that Rick Santorum personally "hooked Planned Parenthood up with a few million bucks," and that this isn't a case of picking a small bit of funding out of the context of a much larger bill in order to create an easy attack, I have a bridge or two I'd like to talk with you about).
The rulebook clearly shows that all three code violations issued to Williams were correct and the Portuguese official pointed out that umpiring is not a case of pick and choose.
Factor in games like FarmVille, massively multiplayer online games such as Entropia Universe and World of Warcraft and other virtual services and it is a case of pick your own number.
"It was a case of pick your moment, with Izale's first goal since his comeback, Daniel Powell topping off his new two year deal with a wonder goal, and then Stephen Gleeson scoring the last goal on his comeback from long-term injury," said Robinson.
It was probably a case of Pick's disease (Schnitzler, 1911).
In frontal cortex from a case with the P301L mutation in Tau and a case of Pick's disease, FSB labelled tau inclusions, indicating that it binds to all human brain tau isoforms in a filamentous state.
