Such a long questionnaire is problematic on methodological and ethical grounds. Methodologically, you will have problems associated with respondent fatigue (low response rates, and low quality of answers). Ethically, it may be hard to justify such an imposition on the respondent's time.
Indeed, I agree with Achilleas! The rule of thumb for most surveys is no longer than 15 minutes (although I don't know if that was empirically derived or someone just came up with the figure and the rest of us just follow it).
Another problem we face with long questionnaires administered to rural or low-educational-level respondents is that the process ends up taking even longer: Those who are not 'acculturated' to responding to survey questions often treat an interviewer-administered interaction in particular as a conversation, and supply conversational responses that are not easily coded by the interviewer. So when asked "Would you say your health in general is excellent...poor?", they go on to tell you about their health status, rather than choosing one of the given response categories. People having experience with questionnaires know how the 'game' works and what is expected -- but when respondents violate these expectations, questionnaire administration becomes very long and difficult.
I am totally agree with Gordon if the lengthy questionnaire administered to rural people, they often take the interview as conversation that take too long. They lost their interest and sometimes leave the interview incomplete or start giving random answers too. So it is necessary to keep thee interview schedule short or make it interesting and enjoyable for respondents.
While I was working for an international survey company in partnership with the FCT Transport Secretariat, Abuja, Nigeria, I encountered a lot of people in the process.
Part of my job then was to administer lengthy questionnaires to busy individuals during work hours or while they were going to and from work.
I was challenged with the task of gaining my targets audience, and administer a 10 page questionnaire to people I have never met before, mostly those in a hurry. It took some attributes to be able to get the work done.
First I had to be more polite than my usual self, wear a nice look even when I am exhausted and most of all, be tactical in administering the questions.
I was prompted to write about the topic you seek answers on because years after my experience on the job, a Corp Member serving in my establishment walked up to me and requested I help her with the answer I am about to share with you. She had an interview for a one year contract job on the topic.
I asked her to seek help from Google, but to my greatest dismay, there was no concrete answer available in the search engine.
I gave her answers from my experience and iit actually gave her the job so I decided to share the information with other researchers that might seek the same help by writing about it. You can check it out here http://www.thetotalentrepreneurs.com/problems-faced-by-interviewers/