Theory: With an AC circuit adding capacitors will cause the current trend towards leading
Because with a resistive / capacitive parallel load, the total current is the vector sum of pure resistive current (current in phase with voltage) and pure capacitive current (current 90 degree lead from voltage). If the two components are Ir and Ic then the lead angle is atan2(Ic,Ir) which is 0 for Ic = 0, Ir > 0, and pi/2 = 90 degrees for Ir = 0, Ic > 0. So you are always between 0 and 90 degrees lead for RC parallel loads. It's not like the lead angle is proportional to the capacitance.