The only time I didn’t use one some gelato autos I grew got taller than expected and then put on some real heavy buds. At that point it was too late to deal with effectively and I had to tie all the tops to whatever I could to keep them from bending over under their own weight. Lots of folks will trellis during veg and put another trellis above that to support the tops during the flower stretch. I’ve always gotten away with just using one.
Much luck with the grow.