its not necessary, i find that the lifting onto a branch from climbing, and climbing up and down is good exercise. you could add maybe one but you are limited in space. from the looks up in though, you could add a diagonal branch in there somewhere, not important though. your cage looks good, veileds arent as solidary as most chams so the foliage is not too bad for him.
well i know my panther loves to climp so i gave him lots of vines but id like a bigger plant so when i got her i decided to get the hibiscus in that picture and sort of fill the terrarium. she is able to climp from one perch to another but i might buy a small bendable vine to put in there. Once she starts laying eggs im going to upgrade to a 18x18x36 so i have enough room for her laying bin, then ill have that little bit of extra room to work with better But thanks for the tips!