In my progression, I had a phase between your level 2 and 3 where I focused much of my practice on Tor's strategy of (mostly) center ball shots, using the tangent line to stay on the right side of the shooting line. The biggest benefit of this was that it really made me focus on working backwards from the last ball I wanted to pocket, depending on 8 or 9 ball.
As I noticed a pretty significant improvement, I went to your level 3 where I would try and land the cue ball on a 3x5 index card. Some idea I got off of a utube expert Im sure. I found that I was not very good at it, started getting frustrated, and my position actually suffered. I went back to focusing on right side of the shot line. I am definitely going to give your zone idea a try. How big are the zones you create on a typical shot?
Awesome! Great job developing your game!
The size of your target is not constant. I have a theory of pattern play I call "Gun vs Target". The target is the area I have to hit on the table to be in good position. The 'gun' is the cue ball move that I am using to hit that target.
I came up with a metric I use to rate how good different cue ball maneuvers are. I call it 'scatter'. The idea is if you were to set up a shot ten times and try to play your cue ball to a specific point, and you were to mark each of the ten landing spots with your cue ball, how tight is the grouping? Are all ten spots exactly on a dime? Are they 10" apart? Are they 3' apart? That is your scatter for that shot. So a stop shot might have a 2" scatter, but a two foot draw shot might have a 2' scatter.
For patterns to work your target has to be as big or bigger than your cue ball scatter. The gun has to be able to hit the target!
So you can play to a 3 inch target if you are using a 2" scatter stop shot. And you can use a wild reverse four railer cue ball maneuver with a 48" scatter if your next ball is hanging on the side pocket and you just have to end up on one half of the table. You don't always need big targets, and you don't always need accurate guns. The gun just has to hit the target.
As long as your gun hits your target you won't be trying to get position, you will just GET position. The same way if you always have 95-99% shots you will rarely miss the pocket, if you have guns that hit your target 95-99% of the time, you will rarely miss the target or get a tough shot.
What I have found is that a lot of problems with people's pattern play isn't just target creation. It's that they are using bad guns without enough control to hit the targets they want to hit. Without the right guns we can talk patterns all day long and it won't happen. If a beginner only knew how to roll a cue ball with center, you could talk all day about targets and it would do no good. They just are lacking the tools needed to control the cue ball. Many players just don't have the right tool box of cue ball moves (or don't know which ones to turn to for best control).
When I play there are ten cue ball moves that I use as I've found they give me the best scatter while moving my cue ball up and down table. So when I teach I try to help people learn and control these shots so they have a reasonable tool belt to start making patterns viable. This involves filling in gaps in knowledge about how these shots work, where they go, and how to adjust, as well as smoothing out their technique (better tip accuracy stemming from smooth cueing with good timing). And then of course we have to put in hours hitting those shots to allow the time to develop confidence and control.
During my sessions I start by developing guns, then look at patterns using those guns, then developing more guns, then looking at more complex patterns. We start with the basic moves and practice running open 8 ball racks, and by the tail half of the session we are working on more advanced moves and taking it to the streets with rotation run outs.
Getting back to your question, the targets should be good enough to happily play from any part of them, and big enough to hit!