Task batching
Task batching is grouping similar work and running it in one go, so the cost of switching between kinds of work is paid once instead of a dozen times.
Task batching means collecting work of one kind and doing it together: the calls in one afternoon, the invoices at month end, the reaching out on a Friday. The claim is not that each item goes faster. It is that the transitions get cheaper, because you set up once and put away once.
The cost it targets has a name in the research. Sophie Leroy's 2009 work on attention residue found that part of your attention stays on the previous task after you move on, most of all when that task was left unfinished, and that the residue measurably degrades performance on the next one. Switching between kinds of work costs more than switching within a kind, which is the entire basis of the technique.
It has a limit that is easy to hit. A batch is a delay by design, so anything time-sensitive gets worse inside one. A reply that would have taken two minutes on Tuesday sits until Friday, and by Friday it is late rather than efficient. The usual compromise is to batch by kind and keep the batch frequent enough that nothing important can rot in it.
Why it matters
Keeping in touch is the most batchable work there is and the least likely to happen without a batch. Each message is small, none of them is urgent, and starting is the expensive part, so ten of them together cost far less than ten spread across a week.