Practise the words you saved
A ready-made deck will teach you the words it contains. That is a reasonable way to learn someone else’s list. It is a poor way to learn the word you met on Tuesday and could not use on Wednesday. Practice only helps when the word in front of you is the one you actually failed to keep.
Begin with what you saved
If the word is not in your notebook, you have no sentence to hang it on. The exercise is a puzzle, and a puzzle has no stake. The session should be made of words you saved: the page, the person, the reason, still attached.
Browse the cards when you want to reread them. Recall a word from a hint when you want to know whether it is still there without being shown it. Take a quiz when you want the word to survive a question rather than a glance. Those three are in the free app, and they use your words.
Further games open with Vocabulary Premium. They use the same words. The practice can get wider. The notebook is not replaced by a deck.
Stop when your words are done
A session is finished when your words are finished. If you saved two words this week, the session is two words. That is not a thin day. That is the length of your reading. There is no pile underneath waiting to be cleared, and no score invented for a day you did not have.
The words you still hesitate on are the ones worth the minute. The words you already know can wait their turn. A deck that mixes both, in an order that ignores which is which, spends most of its time on the ones that did not need you.