If I have X reviews Monday, and Y reviews Tuesday, which timezone am I following?
Tangentially I also just noticed getting an extra 200 items for review after taking a break, and it’s only 9:30 PM 
1 Like
I’ve noticed that it always seems to be 7AM EST, seeming to move with US Daylight Savings time.
1 Like
The timezone you’re following is automatically determined/derived when you log into the website. This may be muddled if one uses a VPN 
Reviews come available 4 hours into the new day to your “local” timezone (the one derived from your browser @ login), which is how Anki works by default IIRC.
E.g. You will have X reviews on Monday @ 4 AM local, and you will have Y reviews Tuesday @ 4 AM local.
For a current fix–if your timezone doesn’t match your current location–logging in and out will update your time zone if the browser correctly reports where you’re located 
For a more permanent fix, I think we could probably expose one’s timezone as a setting.
2 Likes
For a current fix–if your timezone doesn’t match your current location–logging in and out will update your time zone if the browser correctly reports where you’re located
Does that mean we hypothetically can return to a previous day if we log in again in the “past” so to speak? I guess my concern is, if I fly to Asia, which is like +15 hours, will I irrecoverably lose a cycle of lessons?
1 Like
There may be some hourly gaps between timezones that results in a “longer” lesson cycle or “shorter” lesson cycle, but I don’t think it entirely wipes out a cycle. We store timestamps in UTC and do calculations/conversions which results in a more “absolute” lens of when the “next day” occurs, give or take some hours due to local timezone offsets.
But I think travel time alone would make it difficult to be encumbered by these “longer” and “shorter” lesson cycles as enough time would pass on the plane ride over that one would already be in a “new day” w.r.t. UTC. If not, that travel time would eat away the hour offset between timezones 
Not sure I understand. For a concrete example, if you take a 12 hour flight from California to Korea on day 1 at 12AM midnight, you will actually land in Korea at 5AM on day 3. 12 hour flight + 17 hour time difference = a day + 5 hours. So unless there is some magic going on behind the scenes, you are missing the day 2 cycle.
I flew to Korea last October with those flight times, but my laptop was still on PST, so nothing was effected.
Timezones can be notoriously confusing to discuss
Here’s a useful link which shows the timezone offsets as well as UTC:
Since we store and do calculations in UTC, we only track the “absolute” amount of time passing. In your example, that’d be 12 hours. You can see in the chart what the UTC time would be whether you’re in California or Korea.
The current “lesson cycle” may be altered a bit because of how the “logical” day changes across timezones.
By “logical” day I am referring to how our app and other SRS apps allow you to review up until 
4 a.m.
Whatever is 4 a.m. local time is the user’s cut-off in UTC time.
Referring to the chart, the cutoff time would be 
12 p.m. UTC while in California and 
7 p.m. UTC while in Korea.
So, flying from California to Korea, one’s “lesson cycle” is technically longer now, since the “new day” cut-off changed from 12 p.m. UTC to 7 p.m. UTC. You’d have to wait 7 more hours before the next cycle begins, compared to just staying in California.
But this would be difficult to notice or catch, as–more often than not–the difference is “eaten up” by travel time.
In conclusion, you rarely “lose” a “lesson cycle” but you may have a small hour adjustment between timezones depending which timezones you’re switching
The predominant way you would “lose” a “lesson cycle” is unfortunately due to the raw hours of travel times/time away from the app. 12 hours flying is still 12 hours away from the app
One could argue that–for example, flying from Korea to California, you have to readjust your daily cycle 7 hours back from to UTC, which may make you inevitably lose the cycle entirely–but it’s hard to find a combination of timezones which results an absolute “lesson cycle” loss.
There may perhaps be a unique edgecase which results in “losing” a lesson cycle, e.g. the hour difference between “cut-off” times encroaches into 20 hour differences, which would make it extremely difficult to do your lessons/review for the day, but I wouldn’t be sure of the combination
2 Likes
Oh okay yeah that chart really clears things up thanks, very neat.
Okay so to recap you are guaranteed one cycle unlock every UTC date. It’s not really an issue between CA/Korea because the cycle duration is either 24 hours ± 7 hours, so at worse 17 hours instead of 24.
I guess it’s really only an issue if you are UTC+5, UTC+6 etc and you fly to UTC+0. For example, if you fly from Korea to London, the flight is 11 hours, but the cycle is only 9 hours long.
1 Like
That’d be a good example but yes, you’re basically guaranteed access to a lesson cycle, as long as you plan around your travel time accordingly.
I would be curious how many users take advantage of the 4 a.m. cut off
Well not if your flight 1 hour before reset, then the only way around it is to not plan flights before reset. In any case my main worry was that proc’ing the new day would be irreversible. Like you could have programmed this to be path dependent - like increment the day upon time hitting the cycle start. But from experimenting it is state dependent and reversable.
I would be curious how many users take advantage of the 4 a.m. cut off
I have. I have started reviews at 2am before. I’ve also stayed up till 4am and done reviews right away a few times. Especially at the beginning, I would be too excited to unlock the new items, so If I was awake late I’d stay up an extra 1-2 hours.
1 Like
The 4am cutoff is good for me. I’m usually awake past midnight but not beyond 4am and that time period is when I sometimes do my HH time and for me, I consider that part of the previous day.
1 Like