This rule doesn’t just apply to the order in which you do tasks, it also applies to the structure of a task itself.
I’ll give you an example which I regularly come across in my own life. Something I often have to do is put the tables and chairs out for one of my seminars. I use folding tables which are kept in a storage cupboard. Three folding chairs are put out per table. These are kept on a chair rack.
Now which do you think would be quicker?
1) Get out one table, put it in the right place, unfold the legs and turn it over. Then get three chairs off the rack, open them and put them behind the table. Repeat this process one table at a time until all the tables and chairs are in position. OR
2) Get out all the tables and put each of them on the ground with the legs uppermost and still folded. Then open the legs of all the tables. Then turn all the tables over. Then put all the folded chairs on top of the tables. Then open all the chairs and put them behind the tables.
As I’m sure you’ve realised the answer is 2). It’s not just a bit quicker. It’s a lot quicker (and I have tried both ways so I know from experience!). What’s more it is a lot less boring. And what’s more if you get interrupted and can’t finish it completely, it doesn’t matter so much.
The key to efficient action is whenever possible not to do your actions in the sequence ABC ABC ABC but instead go for AAA BBB CCC. However, funnily enough, ABC ABC ABC often seems more natural at first and we often find ourselves doing these tasks in the less efficient way.
Have a think about some of your repetitive actions. Are you doing them according to the AAA BBB CCC formula? Take cleaning a house for instance. Is it quicker to tidy, dust and vacuum each room in turn, or quicker to tidy every room, then dust every room and then vacuum every room? Another example would be filling in a spreadsheet. Is it quicker to fill it in row by row or column by column? I’ll leave you to answer that one!