I can confirm that I also have "long writing times" occasionally with my D800. It happens randomly and does not have anything to do with shooting bursts of raw images. In fact, this weekend while shooting "Medium-fine" files, it happened. I am using SanDisk Extreme Pro 32GB cards (both CF and SD). The camera is set for CF primary and SD for overflow. You guys suggesting filling the buffer and then having to wait have not read the original poster completely. It has nothing to do with "bursts!"