Stone Sky Sea is...well, it's a tool. It is great for when one is first learning their rotation, and it's good to do rotation reps on to keep oneself sharp. However it's common and biggest complaint is that it does not prepare one for mechanics.

What does this have to do with "practice instances"?

Well it's simple. My static and I recently got a tip that the Binding Coil of Bahamut: Turn 4 can be used as a practice area for positioning mechanics in Weapon's Refrain. Seeing as the phase we're practicing is a good 8-10 minutes into the fight, and will only go longer in there, we decided to give it the old whirl. While doing this, I thought "Hey, this is a pretty neat concept. Just an instanced staging area where the group can practice positioning. It'd be neat if we could set up things like dummies and timers too."

Well, that's my suggestion; it would be awesome if we could have some sort of instanced training room, that 8 people can go in. Inside, we could set up target dummies and timers to replicate the fight we're practicing (have it be user-defined if one is trying to keep mechanics obscured, as was the case with the awoken mechanics). It's one of those pie-in-the-sky ideas, but maybe it'll get seen and get some support. Till then I'll probably use Turn 4 as a staging area, because even though I have to imagine everything, it's still a great little arena to use to get an idea of positioning.

As far as the second suggestion? Just a QoL I wish was already implemented. Be nice if we could have preset waypoint setups, either through macros or something. It'd save a lot of time when inevitably the group has to reinstance into a trial or raid.