I sleep angled. What's important also is the tension of the hammock. It took me a couple nights to get it set up the way I have it now.

What's important about the tension? To have it tense or not tense or however, as long as it's comfortable or adjusted by some rule of thumb?

(I've not met a hammock)

Too loose and your weight isn't distributed as evenly as it could be. Also, too loose means a lot more curvature, which puts strain on your knees (or so I've found, as I have a testy knee).

I think I'd say you know when it's set up properly when you feel almost weightless in that the hammock suspends your weight evenly. I wouldn't go by pictures of hammocks that have been set up as many are way more loose than I'd consider livable.