When using ones 3rd eye to visualize a better future does repetition help or hinder the process?
In essence does the repetition become meaningless after X number?
If I understand you correctly, your question is specifically about getting yourself a better future using a 3rd eye visualization method.
This pertains to us being the creators of our reality, which some call it the Law of Attraction.
The basic idea is that each one of us creates their own reality through their thoughts. This applies to our physical reality, to our dream reality, to our astral projection reality, to our afterlife reality, but in the physical, due to the space-time, this creation happens at a slower rate, allowing us to practice and improve our creator skills.
Your subconscious creates your reality based on your beliefs and expectations. If you want to create a certain reality, inside the limitations imposed by the laws that govern the physical, you have to communicate that to your subconscious, and to allow it to happen, unhindered by your beliefs, expectations, fears, doubts, etc..
To do that you have to open a communication path from your conscious to your subconscious, in other words, to enter a trance state, then give the desired suggestion. There are many methods people use to do it. Some use chemicals, some use rituals, religious or not, some use all kind of other "procedures". Most, maybe all, the non-chemical methods try to induce a hypnotic trance, even if their practitioners don't understand that.
In your case, the 3rd eye visualization of a better, desired, future, you try to get into trance by concentrating on your frontal lobe, increasing its activity, and give a suggestion to your subconscious through visualization. Doing this mechanically, most likely, won't succeed, because you don't firstly get into trance and then give the suggestion.
Repeating it many times, both when you do it, and doing it repeatedly, increases the chance to hit a better condition, and get your suggestion through, but it doesn't guarantee it.
A better approach is to get firstly into trance, then, while there, to give your suggestion. It isn't necessary to repeat the suggestion neither at that moment, nor to repeat the process. You can repeat it, but it isn't required, and it doesn't improve the odds.
What you also need to be aware of is that your beliefs and expectations might work against your desired outcome. You may want something, but you don't believe that you'll get it. You may want it, but you focus too much on the fact that you don't have it yet.
Basically, your subconscious creates your reality from ALL your thoughts, ALL the time, not only those you have when you do your visualization exercise. It may be that, when you visualize, you start approaching your target, but during the rest of the day your conscious, and unconscious, thoughts push your target away.