Depending on the subjects and length of the questionnaire, here are a few guidelines:
If the questionnaire has many topics and is not related to a specific incident, ask all your IT users to complete it once a year. If you have more than 1,000 IT end users, ask a sample of 25% to complete it each quarter. This creates a quarterly monitor, without having to ask about IT performance more than once a year. If you have more than 5,000 IT users, you could ask a 1/12 of your IT end users to complete the questionnaire each month.
If you use a very brief questionnaire – around two or three questions – you could easily ask the same group to complete it each quarter.
If you ask questions on how the service desk handles incidents, you could easily organize this by sending short online surveys on a daily basis and within 48 hours after a call/ ticket has been closed.
Of course, the exact frequency also depends on the subject and the possibility to make changes. In addition, the acceptance and participation response rate depends on how you communicate the survey: prior, during or afterwards. You must explain why you are running the survey and what you plan to do with the results to benefit the user and the company. But, even more importantly, you must communicate what you have done with the results. As few as one action or good example will create a basis for future surveys and make surveys an integral and logical part of your IT operations.