On a similar line to Scott, the thing that annoys me most is at adjournment time (OK, I find that annoying enough), you then ask which date the opponent wants to play on. Then, wearing a surprised expression - what question was I going to ask? - they then hunt for their diary. The diary is rarely optimally placed, it's usually crushed beneath various things in their bag. I switch my phone on to look at the calendar there. The conversation might proceed:
Can you do next week?
No, sorry, I've got a game then. You could come to our venue next Tuesday if you like?
No thanks, I'm the home player, you forced me to adjourn, so you can come here.
Well, I can't do the following Tuesday because I've got a Cup game in the <someother> League. etc.
After many minutes of consultation, both with the diary, the guy in their team who adjourned in another game, and the guy on their team who has to be coaxed into giving them a lift because neither of the adjourners drive, you then agree a date and venue - which was not necessarily your own despite your earlier principled stand - to continue the game. (Why is it the people who choose adjournments are always the people who are least able logistically to actually adhere to them?)
And then you agree a draw or resign by e-mail a few days later.
Adjournments would be so much less painful to endure if the people who chose to adjourn were actually prepared for the eventuality that they might arise.