The person is explaining something, that he thing is the most important thing on the world. Like for example, how he had caught a 1 kg fish last week, repeating the same information 10 times.
There is always a way, to just tell him, to shut up or change the topic, since it is not interesting anymore. But let be objective here, how many people would do that?
The doodling is one way, how to concentrate better. The mind likes to wander off, when it perceives the action not worth it of its attention. In other words, when it is bored.
But doodling has been found, that it increases the volume of the retrained information.
They proved it, by making people listen to the boring listing of people and places, without telling them, that they will have a memory test later. Then they asked them, who will be on the party, as stated on the list.
The people that doodle were be able to remember 50% more information than the other group. From 8 people, that were going to the party, the doodlers remember on average 7.5 people and noodlers remembered 5.8 people.
But this is, when the subject is not interesting. In that case, doing something mechanical and simple like doodling stopes the mind daydreaming.
When the subject is interesting, that in my opinion the doodling have a mixed effect.
On one hand, the doodling takes away some of the mental power, that could be used on the subject at hand. It lowers the capabilities of the mand, to synthesize the information and sees the big picture while remembering the details.
But on the other hand, doodling help with creativity as well, that can provide additional insights into the material. The simple act of doodling, might be stimulating the brain to connect the subject, that otherwise wouldn’t be connected.
I my experience, it depends on the subject and presentation style.
In reading, the doodling can be distracting, but while listening in the lectures doodling does help.
The subjects, that depend on the details, the doodling usually help me remember.
On the other side are the subjects that relay on understanding, like physics or macroeconomics. Here the doodling isn’t necessary for me, since I seems to grasp the big picture and concepts with no help. Doodles are usually distracting, while my mind finds the connections.
I still mostly use it to strive off the boredom, and not as the memory technique. If you need to remember something and the way it is presented is boring, that give doodling a try. You might be surprised at how much more you remember.