RSTP synchronization is not widely understood and often oversimplified. This post describes how it really works in detail to give you the full picture.
In the comments I received a wish to compare RPVST+ with MST. RPVST+ is Ciscos proprietary STP running one instance per VLAN over 802.1Q trunks. MST is an industry standard which can run multiple instances but not one per VLAN.