A SQUARE STICK WILL PROVIDE MORE STRENGTH BECAUSE THERE IS MORE WOOD GRAIN INVOLVED....THE NARROW END OF A TRIANGULAR STICK HAS VERY LITTLE STRENGTH WHEREAS A SQUARE STICK WILL PROVIDE MORE STRENGTH BECAUSE OF THE AMOUNT OF EXTRA WOOD AND GRAIN SUPPORTING THE AREA THAT WOULD BE SKINNY ON THE TRIANGULAR PIECE.
TRY BREAKING A TRIANGULAR STICK AND THEN A SQUARE STICK. SQUARE WINS......YOU DON'T USE MUCH TRIANGULAR STOCK IN AN AIRCRAFT ANYHOW. NOT MUCH WEIGHT INVOLVED THERE. IF YOU ARE ADDINGSTOCK JUST TO GIVE YOURSELF SOME SURFACE AREA TO ADHERE COVERING TO, USE TRIANGULAR; STRENGTH ISN'T AN ISSUE....JUST MY OPINION..</p>