Independent suspensions are a more sophisticated suspension. They put much less pressure on the springs as the trailing arm supports the wheel load so the spring is purely used as a ‘spring’. They often need re-alignment from time to time but in good quality systems we see they either never wear bushes or only do once they’re past the 100,000km mark!
If you have a leaf sprung independent system probably think about changing the spring between 90-120,000km depending upon the system. The coil spring versions need to be reviewed periodically in relation to the distance between the bump-stop and the chassis.
There is also a very popular rubber torsional system, used on many caravans and these don’t need any toe-in adjustment but need the rubbers replacing when they start to droop.
Shockers are probably the main wear component on some coil independent suspensions and like a car they have a certain life time based upon their use.