Interesting. I was watching some old Japanese dude's video the other day and he specifically said that a cascade starts with an upright branch. I'm guessing this is something bonsai people fight about regularly. lol
You can have an upright portion, or not. If you do, it’s more of a “formal” cascade.
My point was that it’s not necessary. If you have material that naturally has a nice apex, go for it. If you don’t, don’t force one. Even if it’s not a “formal” cascade, you still need to develop an “apex”. On my tree, once I get it back healthy, I’ll do some adjusting to show an apex.
As an aside, unless the tree is something like a Procumbens juniper, it’s always a challenge to keep the lowest part of the cascade healthy. Especially if there is a portion of the tree growing “above the rim”.