I feel like hitting the lines and angles are rarely talked about here.
For me I always thought it would come naturally with form improvements. And while it's sort of true I had to activly change some parts of my form to start hitting lines consistantly.
While some parts of my form got momentarily worse from the changes I do belive that it helped my form in the longrun.
Here's the things I go through (maybe not everything at once) to be more consistant:
I make sure to find a small aim, just like staring down one link on a basket. I also make sure to envision the release angle och full flight I intend for the disc. This is as much about hitting the line as it is about analysing your throw. Did you hit the intended line and is it a disc/angle/release/aimpoint issue.
grip is always important eventhough I change it at the same pace as I change my socks. Also a real easy thing to check as it is done preswing for me.
wrist: So this might be controversial but I currently try to "lock" my wrist to avoid my bad habits of flailing the wrist out leaving me early releases and super releasepoints. its not necessarily me throwing with a stiff wrist but rather making sure it doesnt move in the backswing, pull or when the arm is arcing out.
Another thing that helped me alot that I'm trying to find a different solution to is the whole keeping my head straight forward for as long as possible and letting the shoulders push the head back in the backswing and forward in the followthrough. Had some neckpain recently so trying to find a different solution with a similar effect or atleast loosen up a bit more. The big point here is me maintaining the correct balance aswell as keeping the body closed to the target so that a full committed swing doesnt result in a griplock (I really dont like this word).
Brace: so I belive its rather hard not to strongarm before developing a brace. and strongarming is a real issue when trying to be consistant.
There is alot more going in to the swing that could impact your release, but when the things above click I feel like most misses will be consistant this in turn makes it easier to isolate the issue/fix of the day.
Long rant about my recent process and progress hoping something will help and make sense to you.