The attacks usually take place when topography changes or on sustained climbs. They also tend be more like small jumps or subtle accelerations. Sometimes, attacks are nothing more than maintaining your speed when the others slow down to rest. Paceline is a very important tool in road racing where groups will often spend miles grinding away at each other. Blocking becomes very subtle and calculated.
Most sprints tend to be in small groups and, often, uphill.
A good road race is almost a religious experience. Most people think that endurance is the most important tool for road racing. Nope, it is still speed. California racing is very different between Northern California and Southern California. When my farm program's first set of riders made it to cat 3, I sent them to Northern California for their first road race against real roadies.