basically my top 5 list is identical with jiacheng's top 5. (thanks!)
i just add a remark for the "workload-preview". ANY information on the workload is going to be great, but there are a few points that have to be considered
1. actual day
for the actual day it would be nice to have the information as detailed as possible, that means i would like to know, how many cards, in which ranges are up for review. so if it looks like the flashcards statistics screen would be fine for me.
2. next few days
actually i think it makes no sense to predict the workload for more than a few days, maybe a week, because it depends on the percentage of right/wrong answers. to account for wrong answers the algorithm would have to know how a wrong answer influences the score of the card, same for the right answer. ok, we could also specify that a certain percentage of my cards i get right, on average, but that still does not account for which cards i get wrong, new cards (low score) or old cards (higher score), therefore also cant be predicted if the cards that are wrong will appear earlier or not...
if the prediction (curve?) does not account for learned/unlearned in the days to come, then in my opinion its pretty much useless, at least after just a few days... suppose i have 1000 cards, evently distributed between 100 and 2000 score. it means in 20 days i have seen all of them. some (lets say 5%) come up nearly every day, some (again 5%) i see only once. ideally they are also distributed evenly in these 20 days, practically they are not. in each session i will fail for 5% of my cards (on average). 5% of 1000 cards are 50 cards, so the daily session on day 1 approximately consists of:
- 50 cards (score 100+)
- 25 cards (score 200+)
- 12 cards (score 400+)
- 7 cards (score 800+)
- 4 cards (score 1600+)
if the scores would not change for each day, it would be straight lines (into the future) at 100 cards each day.
5% of these 100 cards i fail, so its 5 cards. so that could mean, all of the 5 cards i failed are within the 50 cards with score 100+. this means that they will come up on the next day again and the workload for the next day should increase to 105 cards. but if the 5 failed cards are "high score" cards, the workload changes a week later (depends on the change of card score).
if differences between reality and theory like that accumulate over more than just a few days, the prediction is useless. it would be like a weather forecast.
so my suggestion is that the future for the next week is a graph of 5 curves, one which displays the workload for unchanged scores (cards that will come up on each day in the future, without considering right/wrong answers), another one, that considers the max right/wrong card limit and all wrong cards are in the lower score range, another curve max right/wrong and all wrong cards are in the upper score range, another curve with min right/wrong limit and low score cards and finally a curve with min right/wrong limit and higher score cards.
maybe adding a 6th curve, just displaying the cards that are up for review on the days to come would be nice, this curve should treat the cards as if they disappear after they are shown the first time, so it basically shows us the distribution of our cards over time. this would show me the clusters of cards with same score, that i suspect in my cards (many cards with score 800 show up on the same day, but only a few in the rest of the week, likewise with score 2000, thats a big workload problem, if they happen to fall onto the same day).
of course all of these curves must also consider the date when they were last reviewed, otherwise they would not be a prediction for the workload. but for the 6th curve it might make sense to switch between date/no date mode, as it could give you a graphical view of card statistics.
the final truth anyway is made up by the user, by answering the cards, but that way we get at least a prediction, where we can say the workload will be between these lines. i anticipate, that when the cards are not even distributed (like in my case) these lines will not just spread out over the future, they might cross each other at unexpected points. from this picture we might be able to say "now is the time to add cards" or to say "forget about new stuff, first learn the old ones better"...
we could say, that the max limit of right/wrong cards is 100% (i never have that

best i can do is 97%) and the min limit is 85%, but i guess it makes sense to make it changeable or if its available to take the actual average +/-5%. the prediction about the score development (scoring algorithm) is anyway available via the session options (e.g. -25% on fail, +10% on success).
3. long term workload
i think a serious longterm prediction is impossible. so i guess, it would be just interesting to draw a line for a month or 2 which is only the line for the real existing workload, not considering the right/wrong scores... could also make sense to join the 2 graphs and let the predictions for the right/wrong cards fade away (change colors to more lighter tones over time, hehe) but i guess scaling the graphs could become a problem.
i hope i made my points clear enough, to be understood, what i mean. its not as easy as it seems to predict the workload if you want a good prediction, but its still necessary to have one. we will only see, what its worth, when we have it, maybe a few more points come up that have to be considered, or some of my suggestions can be ignored... who knows.