Do you mean like the slapstrap? If so this link has some tech info on the different ways these type of straps are sewn and why yours may have had problems.
i Made tree straps exactly like those, out of nylon tubular webbing rated for 4000+ lbs.
the sewn loops didnt hold, well, not all of them have held.
I gave up using them, when a loop snapped, it was SCARY.
I sewed a 1.5 inch long 'X' shape, and boxed it, usiing a zig zag stitch, and non cotton thread.
IM not sure how I could have made it much stronger?