https://www.youtube.com/watch?v=EuPSibuIKIg took less than 45 minutes and was considerably deeper than FizzBuzz. Moreover, it would be easy to do better than the interviewee did. Granted, it's a pretty artificial situation.
There are some things that are really tricky and so they take longer than that to write even when they're less code, but the examples above are not among them. Also, it's pretty often that I've written longer programs than 30 lines inside of 45 minutes.
I know there are people who can do things like that but can't do them in an interview because they freak out, and there are people who can program somewhat but can't do things like that, and they might be better at other things than I am. You aren't going to find out how well someone's high-level architectural abilities can help you steer clear of unnecessary implementation problems in a 45-minute interview, unless they're the same as your own high-level architectural abilities, in which case you can recognize them.
But you can find out if they can write code that works, at least sometimes, because that's a thing that you can actually do in that timespan.
I think most things you can write in less than 30 lines of code or so could be reasonably written inside of 45 minutes. Like this Lisp interpreter in JS http://canonical.org/~kragen/sw/dev3/terp.js or this octal-to-binary converter in assembly http://canonical.org/~kragen/sw/dev3/osmb.s or this Collatz-sequence searching program http://canonical.org/~kragen/sw/dev3/collatzsearch.py or this paren-matcher in Scheme http://canonical.org/~kragen/sw/dev3/pmatch.scm or this paint program in C https://gitlab.com/kragen/bubbleos/-/blob/master/yeso/%CE%BC... or this Unicode Wang tile ASCII-art maze generator http://canonical.org/~kragen/sw/dev3/uniwang.py or numerous other things like that.
There are some things that are really tricky and so they take longer than that to write even when they're less code, but the examples above are not among them. Also, it's pretty often that I've written longer programs than 30 lines inside of 45 minutes.
I know there are people who can do things like that but can't do them in an interview because they freak out, and there are people who can program somewhat but can't do things like that, and they might be better at other things than I am. You aren't going to find out how well someone's high-level architectural abilities can help you steer clear of unnecessary implementation problems in a 45-minute interview, unless they're the same as your own high-level architectural abilities, in which case you can recognize them.
But you can find out if they can write code that works, at least sometimes, because that's a thing that you can actually do in that timespan.