yes, you should expect your case to be 30 mins at most in a real interview.
The reason why it takes so long is that usually a peer is taking a case out of a casebook so he/she will tend to follow the structure that is written down by the authors and try to guide you all the way to the solution (answer to the client's problem - risk - next steps). This whole process can take long so it's common to have grueling 45 - 60 mins cases.
In a real consulting interview, the person giving you the case is much more aware of what he/she needs to test and will not necessarily make you go through all the aspects of the case. I'll give you an example: if you show that your math is flawless since the beginning the interviewer won't probably spend much time on calculations later on and will focus more on other aspects (say brainstorming for example).
In general, if you are doing good in the case this should take less than 30 mins because the interviewer will be happy with your answers and won't feel the need to test you extensively for longer. It often happened to me that when the interviewer didn't even let me give the final recommendations to the client: this can obviously be a good or a bad sign, depending on how you did in the case.