On a teeter rotor with no pitch flap coupling and no hub spring rate, the first flap frequency is at 1/rev, i.e resonance with the rotor rpm. A system in this state has a phase lag of 90 degrees. When a hub spring is added (or an offset flap hinge) the first flap frequency is raised and the phase lag becomes less than 90 degrees. A very stiff out of plane rotor can have this phase lag of 35-40 degrees. This isn't the only factor that influences the geometric arrangement of control inputs vs blade position, though. Pitch flap coupling can be intentionally introduced to either damp out flap responses to pitch inputs or, in some cases, act as a "negative spring" and accentuate flap response to pitch inputs. This is relatively uncommon on main rotors, but can serve to drop the first flap mode below 1/rev.
Generally speaking, a rotor design team does not have to guess at the phase lag as calculating the first flap frequency is pretty straightforward these days. That said, there are more complex rotor stability issues, particularly with articulated rotors in some maneuvers, that can be addressed by shifting control inputs, leaning pitch links, etc. Those adjustments are often made during flight test, even by experienced OEMs.
Also, centrifugal force is "imaginary" to physics textbooks (and perhaps people online) but when working and analyzing in a rotating frame, it is the common and even preferred notation, even down to part names.