The first few nights I spent outdoors in a hammock was in my backyard. I did not have a hammocking tarp and rain was not expected. The skeeters were out so I used a bug net. I was comfortable and everything was going well until after midnight. That is when the dew started to form. By the time the sun rose, my bugnet was saturated and dripping, as was my suspension. I never thought much about it before then but my neighborhood here in SC often has dew or frost depending on the season. So I adapted and started using a tarp full time whenever "testing" in the backyard. I suppose there will be times where there is enough breeze or low humidity where I can do without but a properly rigged tarp not only removes those issues from the list of possible problems, it rules out other problems and can make things quite cozy.
"Live your life so that your children can tell their children that you not only stood for something wonderful- you acted on it"