Designing a PCB is never a true straight forward job.
For example, you might want to add an additional capacitor to your board.
With EAGLE's online Forward- and Backannotation you can simply select the
schematic window, add the capacitor and connect it. Simultaneously you can see
the part and signals being added to the board window.
And it is just as easy to swap pins and gates, change names or draw additional
connections. And as always, any editing function you use can be 100% undone
thanks to EAGLE's outstanding Undo/Redo function.