I get asked about my "availability" a lot for calls, since that's the nature of my job. EASILY half the time, I will say "I'm wide open except between 1:00 and 2:00pm eastern." and I will get a meeting notice for "1:00 pm eastern". Just an hour ago, I was asked about tomorrow, and I said "I'm wide open tomorrow morning, up to noon, perhaps 1:00 pm eastern." Just a moment ago, I got a meeting invite for 1:00 pm eastern.
This is from a very smart, and very literate, attentive lawyer serving as my outside counsel. I'll keep the appointment because there are others on the call, but I can still vent here.
Note: I am reluctant to start calling specific times - "I am available at 10:00 am eastern - because I am usually not the only one on the call, the organizer is usually my internal "customer", and I want to be as flexible as I can be.