FB's (and Google's and Yahoo's) definition of talent is whoever passes their "quiz show" interview
However, yes, you don't need to know the worse case complexity of shell sort for most tasks, especially at the beginning of a project where load demands are smaller.
And of course, it is worth keeping in mind that when you hire an employee that hopefully at some point, the load demands are higher. And it's kind of awkward if your product hits rapid growth, but your engineers are currently busy learning about algorithmic efficiency.
Nobody sane asks about "worst-case efficiency of shell sort" unless you yourself suggest shell sort as an algorithm. But it is expected that you get the general idea of O notation, because it actually does matter for day-to-day work.
And, as a practical interview tip: It's perfectly OK to say "I don't know about this specific case" - just follow it up with "for most sorts, O(n^2) is an upper bound, so if I'd guess, I'd go with O(n^2).", or something like that. It tells the interviewer that you know general principles.
That's the big problem in most interviews - candidates treat it like a test, where there's just the right answer, and nothing else. It's not a test. It's an attempt to somehow, within an hour usually, find out what you know and how you think. Throw the interviewer a bone or two, and help them do that. Silence and short "I don't know" answers really just waste time for everybody.
Humm no. Google interviews are (or at least were) pretty much right or wrong answers mostly.
The best interviewers could do what you say, but for the most part, no.
There are too many internal recruiters of varying ability and agendas, and too many interviewers of varying ability and agendas.
A company like Google can have stated hiring principles and techniques, but in practice it's going to be nearly random.
Correct
"With what gap sequence?"