Lu, the R22 and many helicopters rig the disk
or mast slightly left to compensate for translating tendency caused by tail rotor thrust- in a hover this works well but at speed, the vertical stabilizer and helicopter fuselage are providing heading control and the pilot can reduce tail rotor thrust, which
reduces translating tendency- but the mast or disk is still rigged slightly left- so the trim knob helps alleviate some of that
force felt at the cyclic.
Above there was some argument about disymmetry of lift and what caused the need for slight lateral cyclic during acceleration- this is caused by transverse flow effect (inflow roll) and not disymmetry of lift. Indeed the flapping caused by disymmetry of lift (which by the way IS present anytime the helicopter is moving in relation to the air around it) is subject to the 90 degree phase shift- this is called blow-back (the disk reaching its high point over the nose of the helicopter and low point
over the tail). The pilot simply moves the stick farther forward to compensate for this effect. Lateral cyclic during acceleration is necessary to compensate for transverse flow effect.