Do ridgeline add strength in small solo tarp? (A-frame style)

Certainly I'm not an expert, and the engineers can chime in. But I think the best you can do for a seam is the strength of the fabric itself, so no seam at the ridge line should be just as strong or stronger as the best seam. No?

I can think of 2 other reasons to sew a ridge line rather than the design you suggest.

1) Only 1 seam vs. 2 means one less failure point for tearing/leaking.

2) A ridg line allows you to do a catenary curve for a tighter pitch than can be easily done with a flat ridge line when pitched in an A-frame. Other pitches are harder with a catenary curve.

Neither of these points mean your design won't work and it will save fabric.

Your idea for the 3 piece tarp will work just fine, especially if you put some curve in the hems all around to pull out the wrinkles. On the other hand, there is nothing wrong with putting two pieces together and using the triangles you remove to achieve the taper to make beaks at the front and rear. Either way will make a servicable tarp.

My last 2 tarps have not had a seam along the ridgeline. No problem.