Suggest editing the title to be more informative about the subject of this topic.
Right, they made a gentleman's agreement to adjourn the game with the intention of resuming later. Usually "later" is defined more precisely than TBD and should be.
Anyone familiar with KGS knows how their approach works. The game is effectively adjourned if either player ups and leaves. Mutual agreement, necessity, escaping, individual connection problems and server problems are all pretty much equal. At a later time, one player can click Resume (and do some things unilaterally, like resign). The key thing is that one guy can not restart the opponent's clock running; if the opponent is online he'll get a message that the game has been reopened and may choose whether to join. If he does, the game picks up where it was left off. If the game is not resumed within 6? months, the player who left first forfeits. (*)
A more formal approach, where a specific date and time is set and the clock of the player to move starts running whether he's there or not is a little harsh except in the case of a serious tournament or an appearance in court. That sort of thing should come with an alarm clock to remind and warn players (not typical of court sessions). It should provide for earlier than planned resumption.
(*) p.s.: Does OGS have a mechanism that allows monitoring for excessive escapes? I don't see a way to obtain a list of incomplete games even for myself. Need to facilitate identification and resumption of "adjourned" games.