I have taken a "finished size" template and drawn around it on a piece that was just a little bit too small - and then when I placed it against another piece, I would "compensate" - one seam allowance would be narrower than the other.
If my fabric is not fraying or raveling very much, I will go as narrow as an 1/8 inch seam - but sometimes I will use Fray Check or put another row of stitching in the seam allowance for added security.
If the fabric is "flimsy" - I would not do that. Why risk it pulling out and make a bigger mess?