I always only do the one hour but thats because the full test is actually fairly dangerous for me without a very good reason to do it. I'd get the short one done with little kids to entertain - its already hard enough to keep them happy for that long. The one and only time they had me do the long one (without doing the short one first) I had my sister there as well - thankfully, as I had a hypo in the hallway to the bathroom and the kids would have been completely unsupervised. Oh yeah, and who knows when someone would have stumbled across me.