Speaking to several suspension specialists they dont seem to bother changing them!
From the haynes T5 manual:-
Anti roll bar nuts
Drive shaft nuts
Front balljoint lower nut
Front track rod end nut
Front Suspension strut to swivel hub nuts
Rear shock absorber upper bolt and lower nut.
Maybe different for the T6.
Generally, the nuts are replaced as they are nylocs - I’d use a bit of loctite if re-using. Bolts used are stretch type so once tightened correctly they shouldn’t be reused.
Ian