Honestly it depends right? Do you want to just be decent with it or a specialist?
I'd say there are 4 or 5 pretty common angles to finish the technique. If you just want to be decent at the technique then maybe pick one or two of those finishing angles that you like and get good at those. The cool thing about this sub is is basically works from any angle as long as you keep it locked up and keep trying to keeps your hips facing theirs. So drill it like this. Lock it up just hard enough to hold it in place and tell your partner to move around to try to escape it and follow him around and try to make it so your belt knots are facing each other. On top, on bottom, on your side, mounted, guard, doesn't matter. Just keep that angle and then you'll be able to finish it anywhere they go.
In general the top finishes tend to put a little more crank on their neck and the bottom finishes tend to be cleaner chokes. So I think it's smart to be good at at least one top angle finish and one bottom angle finish.
With this sub as well as the guillotine choke (especially the high elbow) this is what you must do to maximize it to its full potential. The best darce choke and guillotine choke guys rarely try to force just one position to finish. They lock it up and they may prefer a certain way but if the opponent moves around then they are ready to move with it and take it wherever it goes.