Triphyllas require a very long period from the last stop to flowering, and most of them do end up having long stems which can start to look a little short of leaves on the lower part of the stems at show time.

Feeding regularly with a high nitrogen fertilizer can help to stop the lower leaves turning yellow and dropping off.

Some triphylla's such as Insulinde and Taco do take shaping quite well and will break from leaf joints readily if sufficient light reaches the lower levels and sufficient high nitrogen feed is given to stimulate the plant.

I have noticed that the triphyllas (terminal flowering types only) initially have a flowering head at the end of each stem, then a further two heads break three leaves further down the same stems (one leaf back from the initial flower point - see picture), what use can be made of that I leave to you.