Combined with spaced repetition (Anki) to reinforce the memory, I think it's extremely powerful. Anecdotally, it works well - I can recall all of these items on demand, months later.
The next step (which I haven't quite figured out) is to multiply this across multiple domains. I.e. every day, learn 1 French phrase, 1 Spanish phrase, 1 German phrase, and so on. In my (nonscientific) experience, this is more effective than focusing on a single topic.
If you are going to Italy soon you can memorize "non lo so" to say "I dont know" very effectively. But if you are actually trying to learn and retain "some" Italian, you probably need to know more like "lo" is a direct objective pronoun for him/her/it and "so" is the verb essere conjugated in the present tense for io.
If that is added, or you're already just using the desktop client, then IIUC the feature you seek (1 new concept, per category, per day) could be acheived by setting the "new card" number on each deck to "1", provided you've separated each of the concepts into subdecks of a main deck.
You'd be losing FOSS, Linux, and IMHO my favorite feature, the mobile support by switching to Supermemo.
When I was using Anki in school I just used multiple decks. Usually one per class.
There is a significant time / resource difference between one word a day and constant study time where you do learn way more than 1 new vocabular per day in avg.
Depending on well you retain information through a block of constant study time vs. a much smaller, long-view approach to the same amount of material, could be the determining factor on which strategy you choose.
Here's how it works. You basically add everything you're reading to Polar.
Right now it supports PDF and captured web pages. It works offline and your data is yours. It's a desktop app with a webapp+mobile coming soon (like 2 weeks).
Polar supports suspend and resume of reading with "pagemarks" which are basically "boxes" covering multiple pages with a start and end.
This way it's very very clear what you've read and what you have not.
While you're reading you can annotate and take notes directly in Polar.
This includes comments, highlights, but also flashcards.
The flashcards can be sync'd with Anki which means you get spaced repetition built in so you NEVER forget anything.
Here's a screenshot of my current reading:
The progress bar on the right is how far I've read within that document.
All your annotations and highlights are yours. We support markdown export and the on disk format is simple JSON.
It's also Open Source and we'll have a web and mobile version soon. Works on Linux, MacOS and Windows.
It also supports cloud sync so if you have multiple computers you can keep all your data in sync.
If you just want to avoid the cloud you can not use the cloud sync.
However, if you do, you can also use the web version which is coming out soon and which also means you can use it on a tablet device.
The idea is to build out a collaborative learning platform.
However, first I have to attract and audience together that is large enough that could benefit from collaboration.
So one step at a time.
Currently I read all my books and articles in kindle. I think I'll use polarized to read and organize the articles I read and use kindle to read the novels.
If I could see the total usage statistics in polarized that would be awesome.
It's legal to do this for compatibility purposes but IANAL.
Polar is better for creating notes from what you're reading.
I'm working on making Polar better for just plain notes. Getting there.