With a clicker, you can be sure of consistent draw length. Without a clicker, it really is just a matter of continual practice and developing muscle memory. A consistent anchor is really only half of the game. The other half is consistent bow arm too.
Consistent bow arm actually has a lot of components. These include, but are not limited to: angle of your wrist (where the pressure of the grip is on your hand), bent versus locked elbow, angle your arm makes with your body, and low or high shoulder. Play with each of these to see where it most comfortable, maximizes alignment (which will delay fatigue), and where it can be repeatable for you.