Are you sure about getting paid for each completed USDA survey? I am a part time enumerator for the USDA-NASS and have yet to get paid for a completed survey. I am paid a price per hour times the hours put in and it does not matter how many completions I get. 
I agree some of the surveys come at the wrong times but it is what it is. Part of the problem is the lack of practical farm operating experience of the powers in charge and enumerators. I try my best to be mindful of the farmer's time and what is going on the farm.
Also, a lot of the surveys are national rather than regional. It may be corn planting or harvest time in one area and another area may be weeks from turning wheels. I farm also and do not want to be bothered at times. I agree some of the surveys are of questionable value but somebody is looking at the results. The people that look at the results are the ones that determine the role of government in the farm programs (whether that is a good use of resources or not can be debated but is a topic for another thread). What happens with the data collected is WAY above my paygrade. That can, should, and will be debated.  Jim