The hiring process at Twitter, takes me about 2+ months and finally shows the worst thing that could happen for a candidate - Break their own words without respect.
I have been redirected back and forth for quite a long time, to talk with 3 managers, and passed 2 phone interviews, and the HR has formally emailed me that "Congrats! Twitter decides to bring you onsite soon". Then after I talked with the person who supposed to schedule the travel and onsite date, suddenly I get informed that the team fills the position and we continue to try to find you a fit (which they didn't).
The outcome of the interview process just makes me feel awful. If you cannot do an onsite for a candidate, even it is not because he/she is not good enough, let them know in time. Breaking the word is the worst thing you could do to a candidate.