Once you have the rigid and semi-rigid and not mentioned fully articulated heads under control, you realise you have to change all you understand due the spheriflex and starflex heads. The mentioned 3 depends on mechanical hinges limited by a mechanical travel stop or limit. Simply put. Blade must take it from here or you feel it complain in the cockpit as it can not compensate.
How much the blade flap itself depends on its design and construction-metal vs metal spar vs composite. On a 135, 105 etc the blade does it all. On the 350, 120, 365, 332l2 for instance with the starflex/spheriflex heads, the composite blades as well as the head flap and drag. Their are no mechanical hinges in the head, just a laminated spherical stop which balances aerodynamic force vs its own tension torsion design. Simplist way to explain the laminated bearings used extensively is: flexible in shear, stiff in compression. Thus almost like the leaf springs on the rear suspension of a older pick up truck. Together with the laminated spherical stop onto which the blade/ blade sleeves mount is a droop ring that allows the head to tilt around the mast to further allow for movement and correction on the other side. Working of the concept is easiest if you pull down on a 350/120 blade and let it go. You will see the 3 dimensional movement of the droop ring, sleeves and the heart of the system the sperical stop. Add a composite blade and their is loads of movement and compensation for wind, imbalance, etc in the design.