How to maintain a good swing
While you may not be consciously aware of it, your brain has no problem keeping track of your clubhead when it's in front of you because the head is "seeable," either by looking directly at it or through your peripheral vision during the takeaway.
But during your backswing, as your hands cock, the clubhead leaves your visual field, and at this point your brain must rely solely on its network of sensors scattered throughout your body whose job it is to report where your body parts are.
The problem is that when you suddenly deprive your brain of its dominant tracking system (sight), it requires a smooth transition from your visual to your kinesthetic system ― the pass along ― to keep the clubhead going where it should. Turning over every swing to your sense of feel is just asking for trouble because "feel" is a shaky edifice on which to build your swing.
There are two steps you can take to keep your good swing around as long as possible. First, make a blueprint of your good swing: Write down, in detail, what you do when you are swinging well.
If you don't know what you're doing, see your teaching pro and write down what she or he tells you. With your blueprint in hand, you can reconstruct your swing when it starts to go south.
Second, do the following drill anytime your swing goes on wobble: Close your eyes and, from your normal address position, swing your clubhead to waist high. Now open your eyes and check how near you came to your goal; then adjust and close your eyes to embed the feel.
Repeat this closed-open-adjust-closed sequence with your hands at 10 o'clock, both for the backswing and the downswing. This will help you make the transition from sight to feel without a hitch for every swing.