Everyone knows "Mountain Time". It is when you go to the mountains on vacation, and don't spend much time adhering to a strict schedule, instead taking leisurely strolls around the fields and promising vague things like "I'll try to be back for dinner".
3 years ago, when I started work for my current employer, I noticed in Slack that everyone was reckoning time in "Standard Time" year-round. Now imagine my chagrin because I live in Arizona, and "Mountain Standard Time" does not change for DST. Therefore, all my coworkers were citing nonsensical, nonexistent time zones and it was messing up my ability to convert back and forth.
Come to find out that this was some sort of entrenched, company-wide standard that was deliberately imposed. I made a lot of noise about this and appealed to some rather highly-placed directors, because I felt like it was wildly inaccurate and deceiving people; if you schedule a meeting in EDT but you say it's in EST, and we have employees all around the world, who's going to know? You're inviting off-by-one errors. Especially with me who lives permanently in MST.
3 years on, I've been unable to change this fundamentally; while a few people acknowledge DST, 90% of the company still adheres to this crazy false standard.
I just had someone asking me if I'm available at 5pm EST.
Also, your clock can get confused driving North from PHX to Zion National Park.
In summer you start in Mountain Standard Time, drive into the Navajo Nation which does observe Mountain Daylight Time, containing through the Hopi Reservation, which is Mountain Standard Time. Then you end up back in Navajo Nation with Mountain Daylight Time. You keep on driving towards Page which is in Mountain Standard Time. However, when you cross the state-border of AZ/UT you're back in Mountain Daylight Time.
How does this generate off-by-one errors? I am also part of a company with employees in pretty much every timezone, but when they create a meeting the meeting invitation is programmed with the correct timezone so in my Calendar it always shows what time the meeting is going to be for me. I never even have to think what timezone the organizer is...
The off-by-one error occurs when you announce an event in Standard time but really mean Daylight time, or vice versa. While those local to the time zone will often automatically correct this mistake either consciously on unconsciously, those in other time zones (especially where Daylight time isn't used or is on a different schedule) will tend to rely on time conversion tools which will take a literal interpretation of the scheduled time and result in the person being an hour early or an hour late.
The fact that you have to announce timezones is already an error. If I need to schedule a meeting I don't need to select timezones, they're already selected from the timezone I'm part of. There's never room for error by "picking" the wrong thing, since there's nothing to pick. And if my system is programmed with the wrong timezone, then every single meeting will be off-by-N and my calendar will show the wrong time as "now". It would be impossible to miss such an error.
I think your company needs better tools to handle meetings.
It's the same at my company. Teams and Zoom both automatically schedule meetings in every attendees' own time zone. Maybe that person's company still does phone meetings or something.
We don't use any automatic scheduling with Zoom or Google Calendar. Management doesn't send invites to those meetings, they just publish the link on Slack and we have to figure out how to get it into our calendars.
Trust me, at least once I missed a meeting because I was late by an hour due to time zone confusion.
I mostly struggle with Irish Standard Time (used for DST in Ireland) and Indian Standard Time which have the same acronym. :(
Thankfully, I learnt a long time ago to use ISO 8601 and UTC for dates and times. I still revert to PST/PDT if my audience is primarily left coast based.
And I can't say it's ever actually caused a problem, but something about Indian Standard Time being a half-hour offset from UTC has always bothered me so much... But now we're fully off-topic.
And if you've been American since birth, and live in Arizona, one might still not know, since PDT and Mountain Time alternate covering Arizona seasonally. ("Ask me how i know.")
It can also varies within Arizona... one of the most confusing times in my life was driving from California through the Navajo Reservation in AZ on my way to an appointment. Was my cell phone giving me the local time on the reservation? Was it connecting to a cell tower just outside the reservation, giving me DST-less Arizona time? Or a tower slightly further away in Utah (DST?) Or was it giving me the time on the Hopi reservation, which is an enclave totally surrounded by the Navajo Reservation which uses AZ time?
Even in Australia, AEST has a DST flavour and a non-DST one. Queensland does not observe DST while the other states do. You can drive around a roundabout at the border and switch timezones for fun. Or go down there to celebrate the new year twice.
Or go from rabbits being OK to some 5 figure fine if you're caught with one :)