You can, but you run the risk of the comb falling out during handling, at least for the first year, if there is no additional support. The bees will chew the rubber bands off within a month or two. If the sides are not attached well, the comb could break off during an inspection.The fishing line will inbed itself into the comb and form a permanent support if you run it through the holes in the end bars. I have done it both ways and during a cut out, rubber bands are faster but occasionally the smaller pieces of comb will slip down. I use the fishing line on all my new frames to form a support for the bees to build the wax onto. Way better than the wax foundation I used to use.