They work hard, but their task is impossible. In a period of days or, at most, weeks, they are charged with developing a program sensitive to the needs of the country. Needless to say, a little number crunching rarely provides adequate insights into the development strategy for an entire nation. Worse, the number crunching isn't always good. The models that IMF uses are frequently flawed or out of date.
Critics accuse the institution of taking a cookie-cutter approach to economics and they are right.
Country teams have been known to compose draught reports before visiting. I heard stories of one incident when team members copied large parts of the text for one countrys'report and transferred them wholesale to another. They might have got away with it, except the search and replace function on the word processor didn't work properly, leaving the original countrys' name in a few places.