I don't think it's just a function of time. 3-5 questions could easily take 30 minutes to answer. A phone call is just such a larger imposition than email (for

I don't think it's just a function of time. 3-5 questions could easily take 30 minutes to answer. A phone call is just such a larger imposition than email (for many). No time to think a solid response through, research your answer, start after supper finish after the kids are asleep, etc. Email lets the respondent control the conversation, rather than the requestor.