Stay In Your Own Lane!
Part of the road near where I live has a set of winding curves on a steep grade. I seldom drive this stretch of roadway without encountering an oncoming vehicle part way into my lane over the double solid yellow line. There is no reason for this that I can see except that the other driver is either careless or incapable. The lanes are standard width and you are able to see oncoming traffic without difficulty if you look ahead.
This tendency to straighten out the curves by drivers is highlighted by the condition of the lines before they are repainted each year. The part of the line, center or shoulder, on the inside of the curve has in some cases been completely worn away by the tires passing over it. I think that it is fair to say that it takes many sets of tires rolling in the wrong place to erase lane markings.
It seems pretty obvious that failing to stay between the lines is not a good thing for any driver to get into the habit of. There is likely to be other traffic, either beside us or oncoming in the left lane. Ditto for the right lane or shoulder. Yes, the shoulder. This is where you will find cyclists and pedestrians. In fact, if there is no shoulder, you will find cyclists and pedestrians using the edge of the roadway and they are entitled to be there.
As a driver, your aim (pun intended) is to maintain a proper lane position at all times. It's implicit in our highway system because we all share the same sheet of pavement or stretch of gravel. When we don't, we risk running into each other. You are not being overly cautious, you are fitting into a system where safety dictates that we all manage space around us properly to avoid collisions.
This concept also applies even when there are no lines on the highway at all! Our Motor Vehicle Act discusses staying on your half of the roadway before it sets out the rules for roads with lines painted on them.
You might be thinking of interrupting me at this point and suggesting that it doesn't matter when no one else is around. Odd, but I've had many drivers say that to me when I was asking for their autograph on a violation ticket. If no one else was around them, how could I be there? The point that I want to make by saying this is that if you do it right all the time, you will probably have a better outcome when you fail to see or allow for the presence of another road user.
So, what's the best way to confine the path of your vehicle to where it is supposted to go? That will depend on what you are driving and how you choose reference points on your vehicle to guide you. When your vehicle is correctly positioned you will need to know it's limits on all four sides, so choose wisely. Now, keep your eyes up and look ahead, your vehicle should follow your line of vision and you will know it.