putting lots of tension on the ridgeline will cause the hammock to have much more "inital drop" causing the user to have to factor this into the setup, usually having the bottom of the hammock much higher knowing the hammock will drop 2 feet once they weight it. this is not the best way.
as a rule of thumb, always set the straps around the tree as high as you can reach, or at least above head height (unless the trees are very close), the support lines should run at a good 25-30 degree angle and no flatter unless mandated by a long hang. if you have done it incorrectly, the ridgeline will sag while you are in the laying position. this is not likely to happen, but it would only mean that you have things a little too loose. tighten the supports a few inches, lower the straps a few inches. it is pretty difficult to set up with too much sag, most people (especially beginners) will tend to tighten too much anyway, so it is better to err on the side of "too loose" rather than "too tight" because "too loose" and you can see it in the sagging ridgeline, "too tight" is hard to know for sure. i put the straps higher than my head 95% of the time to get a ridgeline that is taut but not under any signifigant tension. the rl will often sag when i'm sitting in the hammock with my legs hanging over the edge, but will tighten up once i lay down.
oh, and i've read here on hf about several hh ridgelines failing from being pulled too tight, so it does happen.