Respect for others peoples time

I do a fair amount of interviews for both print and media. Until recently have I had mostly good experiences.  Notice how I said "until recently."  The process usually starts out where both parties agree on a time that they can both be available to speak on the phone or physically meet in person. You'd think that since you both agreed on a given time that there wouldn't be any problems there. WRONG! If your running late for an appt, common courtesy is to phone/email/text- SOMETHING giving the other party a heads up that your going to be late.  And we do this why??-respectfully so that the other party isn't left guessing, sitting waiting, etc... I seriously wonder exactly how much time people waste in a period of 24 hours waiting for other people to show/call/email etc...

Have some consideration.