IMO, the biggest problem with timezones is that the people who initially created them were fairly short sighted.

That and there have been way too many changes to who lives in what timezone. The one that boggles my mind is that apparently there's a country in two timezones, not like, split down the middle or anything, but two active timezones across the entire country depending on which culture you're a part of, or something. It's wild.

I still don't know if there's any difference between GMT and UTC. I couldn't find one. They both have the same time, same offset (+0), and represent the same time zone area.

I use UTC because I'm in tech, and I can't stand time formats, so I exclusively use ISO 8601, with a 24 hour clock. Usually in my local time zone, via UTC. We have DST here which I'm not a fan of, but I have to abide by because everyone else does.

My biggest issues with time and timezones is that everyone uses different standards. It drives me nuts when software doesn't let me set the standard for how the time and date is displayed, and doesn't follow the system settings. It's more common in web apps, but it happens a lot. I put in a lot of effort to try to get everything displaying in a standard format then some crudely written website is just mm/dd/yy with 12h clock and no timezone info, and there's nothing you can do about it.