#Tip67: Repeat a Change on Contiguous Lines
We want to make a change:
Record One Unit of Work
##0
normalizes our cursor position by placing it at the start of the line. This means that our next motion always starts from the same place, making it more repeatable.
Note: f. is more repeatability than l
Execute Macro in Series
When the f. command is executed, it finds no . characters and the macro aborts.
Execute Macro in Parallel
##:normal @a
tells Vim to execute the macro once for each line in the selection.
Deciding: Series or Parallel
Executing a macro on multiple items in parallel is more robust.