This happened about 25 years ago.
I was helping out an ex-student with her MA Linguistics dissertation (for a different institution), so we'd meet up to discuss the points she was making, including the examples she was using to illustrate her arguments. This meant sessions that could go on for hours.
When she was my student on the BA course, she'd often sought me out for a shoulder to cry on: her issues with the head of department; her family problems (being deserted by her father for a new family); etc. These conversations also took up a bit of time, often a few hours going for a walk or a few pints in the pub.
Imagine, therefore, my receiving a text from her, just saying, "Are you free on Friday?"
Which part of Friday? How long for? To do what? Urgent or not? Where?
I needed the details to see if I might be able to fit her in, because I might have other things to do (hence the "where?" as well for the logistics in case I had to go to another place in London).
Her vague question meant my having to go back to ask for more information. It would've saved a lot of time, not to mention money (I was on PAYG [pay as you go] for my mobile at the time, being on a half salary; as a foreign student, she'd need to be careful about outgoings, too), if she'd spelled it all out in one go in the first place, e.g.: "Are you free on Friday, any time that suits you, to go over my dissertation in the students' coffee bar at SOAS?"
