Schedules are inherently Lawful. They may be malleable, changeable, or in some aspects vary, but inevitably they pin people down to behaving in predictable manners. Unless that schedule happens to be the one for the date and time of the game session, in which case the one highly attributable law is that no mater how far in advance a game session is planned and agreed to by everyone, those commitments don't mean squat.
Why doesn't the game schedule matter? Because more powerful devils (schedules) take precedence. Be it a family emergency or event (excusable), or work (uhm yeah, we're going to need you to come in on Saturday), or a spouse declaring that you can't go to the game (you know who you are).There is almost always a greater devil pulling the strings.
In game terms perhaps we can affix blame to a greater devil known as The Horologe.
This greater devil is assigned to diplomatic duty outside of the Hells, specifically, to Mechanus, home of the most regimented of beings, the Modrons.
Originally assigned as part of a diplomatic mission requested by Primus in a attempt to bargain safe(r) passage through the Hells for the Modrons great march every cycle, and to balance the diplomatic mission of good, The Horologe has found the position comfortable if a tad frustrating.
Corrupting Modrons is not as simple as it seems when the concepts of evil and good are equally valid and invalid to their ethos and function. Of the Modrons presently serving the local needs of Hell's diplomatic mission, less than two dozen may actually have become corrupt and truly evil, though how could anyone, even the Horologe be certain.
The Horologe decided to expand reach outside of Mechanus and into the material plane. This required new servant devils whose purpose is to corrupt through the pressure of ever tighter schedules and deadlines, and tempting victims to cheat, lie, and commit other offences in order to make deadlines or appear to have met goals. This also works on other souls by convincing them to bully their subordinates, through time pressure, creating a domino effect of corruption.
Unique (undergoing promotion to arch-devil)
HD 18, HP 99
Saves as F18
AEC page 115 - standard arch/greater devil abilities
Only harmed by magic weapons
Chance to gate in 1d6 Pentadrones (Modrons) or 1d6 Clockwork Devils (65% chance of success for either). Flip a coin or choose.
The Horologe is a 9' tall humanoid devil with brass mechanical clockworkings intermixed with the organic majority of its body. The right arm appears to be mostly mechanical. The left eye is replaced with an ornate time piece. A whirring and clicking sound always accompanies The Horologe.
In addition to spell and melee damage, 3/day The Horologe can release a scalding burst of steam in a 30' radius centered upon itself. All creatures not immune or resistant to fire/heat damage take 9d6 damage (half if save). The cloud of steam also provides half cover for everything within it until the end of The Horologe's next round.
The Horologe attacks twice per round with the right arm as a +3 weapon of wounding. Damage: 1d8+5 and 1 additional damage per round (per wound from this weapon) until healed.
If The Horolge feels seriously threatened the order of events will be: Time Stop - move to include as many enemies as possible and use the steam burst, move to include others left out and repeat, then teleport without error to safety.
HD 5, HP 33
Save as F5
Attacks: 2 claws 1d6 each, or 1 weapon with bonus +2 to hit and damage (non-magical).
Clockwork Devils are human sized mechanical appearing lesser devils with whirring gears, and pistons, and various types of timepieces for a head in their natural form. They are able to assume a human appearance when attempting to fulfill their purpose of corruption through time pressure.
Corrupted Modrons will have a physical trait that may clue PCs in on their unusual nature. Maybe small horns, or red eyes, or their choice of weapon, etc. They also have a feature common to devils (DM's choice).
Note: Any artist out there feel like tackling the art for The Horologe and Clockwork Devils? I can't pay a lot, but I am willing to pay. No art for Modrons since those are WotC property to my knowledge.