The Sun remains in one zodiac sign for about 30 days. That is 30 years in a progressed chart. If you live long enough your sun sign is changing twice in a life time. Often this period of change is mirroring a changing life style.
A dramatic example?
On October 9, 1967 Che Guevara was executed after a disastrous attempt to create a revolution on the mainland of America Latina. His Sun had move to Leo in 1966, when he left Cuba. In 1997 his body returned to Cuba. That was when his progressed Sun moved to Virgo.