When using the Incremental Design Flow, I make a change to one logic group and then reimplement. Instead of just reimplementing that group, other groups are also reimplemented. Why does this happen?
Check to see if the changed logic in the area group affects context logic in your design. The context logic might drive logic in other area groups, which in turn would change their logic. To avoid this, place as much logic as possible into area groups to minimize context logic.
Check to see if your guide file was created using the "-incremental" flag rather than the "-leverage" flag or the "-exact" flag. Not using "-incremental" results in a flow mismatch, and causes all area groups to be reimplemented. To avoid this, be sure to use "-incremental" when generating your guide file.