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ReneDescartes wrote on 06/25/13 at 02:34:52:
Great point, I had not quite realized this.
The modern time controls, with their SuddenDeath second segments, do pressure the chess game to end with fewer total move-pairs. They affect the LENGTH of the game, whereas the initial purpose of the clock was to affect the PACE of the game.


ReneDescartes wrote on 06/25/13 at 02:34:52:
This point now has a clear consensus of support in this thread.


ReneDescartes wrote on 06/25/13 at 02:34:52:
Adjournments were a problem because they demanded so much work during what was supposed to be recovery time. The fairness aspect was secondary, or so it seemed to me.
But...
Adjournments seem essential IF a primary goal is to not have the clock and time control affect the LENGTH of the chess game.
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First of all, it is important that it didn't used to be the case that the game lasted a fixed number of minutes. The time controls dictated the maximum average pace of play, but not its length.  Through adjournments, players could keep on playing at 4 minutes per move indefinitely. This was desirable, as a chess game was not distorted by artificial time pressure as long as one side did not pose intractable problems for the other side. 

Thus once adjournments were ended, there was a strong tradition already in place of intermediate time controls. I believe a game feels more classical with a time control at  move 40, and that this is a legitimate way to maintain continuity with the past. An average pace is set--today more likely 3 minutes than 4, unfortunately--but it is set nonetheless. The game proceeds as a classical geme did, at a measured pace. The sudden death period at the end, if its limit is almost reached, feels like a sort of tiebreak appended to a classical game. Having just played a game in 150 min. this week, without an intermediate time control, due to a faulty clock, I must say it felt strange. ErictheRed spotted the biggest problem with that--not so much the players that will leave their clock running out of malice (those guys can always spill coffee on you), as the players that will use all their time up front without much benefit to the chessic content of the game.

Finally, I would like to see more tournaments with adjournments permitting computer analysis. It seems to me that adjournments, far from granting an unfair advantage to anyone, would exert an equalizing influence today. You don't have to have Geller working with you at 2 AM to find 47...Rxh7!! It might be a bit like an adjudication, but it would be preferable to time pressure losses. And ENDGAMES would be played well again, perhaps even better than before because of the Centaur analysis that would occur.

People like planning ahead to fixed points in time.

I think extra time for longer games is the main reason. A single time control is not adaptable to the length of the game and tends to result in endgame time scrambles for the longer games. Some games simply have a both a tense middlegame and endgame, and serious tournaments often account for this possibility by providing a second time control. Tense situations like these are difficult to anticipate and factor into time management. The second time control is designed to preserve the quality of play in the later stages of the game. A "per move" time control establishes an initial pace. Of course, time scrambles are bound to occur, but I think the idea is to minimize the number of games running to the final hour under these circumstances.