How many drills or years before stroke is "hard wired" & conscious mind never interferes?
It takes as long as it takes. If you spend 20 minutes a day working on it, you will find it happens quicker than if you spend 2 hours once a week.
It is said that it takes 21 days to develop a new habit. But, just as you need to change the oil in your car every 3000 miles, you also have to maintain your stroke building practice.
Everyone is different, so you might get it hard-wired more or less quickly than others. But if you aren't working on it, it's not happening at all, and if you don't put in the time to maintain it, it will fail when you need it most.
There isn't a fixed time to reach an end goal in pool. It's a process of continuous improvement. Enjoy the journey, and don't focus on the destination.
Steve