"It's quicker to deal with it now"

Answer it now and it's gone. Leave it and it sits there all evening and you deal with it in the morning anyway, with the extra cost of having carried it. Now is cheaper.

Look at what happens after the reply. You answer Priya about the numbers. Priya, who's also on her sofa, reads the answer and thinks of the next question, because she's now in the deck, and the next question arrives at twenty-five past nine. You answer that. By ten you've had four exchanges about a deck that's due on Thursday, and Priya has too, and both of you have spent an evening on it that neither of you planned. A reply is an invitation to reply. It's the one thing you can do to make sure there's a second message tonight. The earlier book The work will still be there made the same point about the evening email session, that emptying an inbox mostly refills it.

Then look at what "gone" means. The question is gone. The subject isn't. You've now got the deck in your head, and the version numbers, and a faint sense of whether Priya sounded worried, and all of that is in the room with you for the rest of the evening. What you carried by not answering was one unread message. What you carry by answering is the work.

Liuba Belkin, William Becker and Samantha Conroy surveyed 570 working adults about email outside working hours and found something that bears on the "quicker" claim. What predicted people's exhaustion and their trouble switching off from work wasn't how long they spent on email after hours. It was whether they felt expected to monitor it. The time, they write, was not the main driver. If the cost of the evening email were the minutes, then the four-minute reply would be a good deal, four minutes and done. The cost isn't the minutes. It's the state of being on watch, and the reply confirms the watch.

There's a fair objection, which is that some things are quicker now. If Priya's question needs a fact you'll have forgotten by morning, that's a reason to send a one-line note to yourself, not to Priya. If it's a real emergency, that's chapter 22. For the ordinary question, the morning version takes the same four minutes and doesn't come with an evening attached.

So the arithmetic goes the other way. Now costs four minutes plus the reply to the reply plus the deck in your head until bed. Tomorrow costs four minutes. The word "quicker" is doing a job, and the job is making the evening feel like the efficient choice.