I find myself exercising in different lengths and periods throughout the day and week. I've settled on a preferred way to "add" things manually without leaving the practice mode. I have my vocab-add-setting to "time-to-time" or "pretty frequently" and then I've set all my lists to pause.

This will add things from the queue until it's empty, and I can live with that. Queue-things are often things I find around so that's fresh anyway.

When I want to add things, I now "Press Play" on the lists that I want to add from and then I pause as soon as I'm satisfied with the "added-bar" state.

Maybe a "+"-icon besids the play/pause would make it even more convenient to "add" exactly the number of words/characters wanted.

What about having a daily target of X words that is added and after that, you need to manually add?

We're actually building the manual add button now. Hoping that that will be a very simple way to give yourself a lot of control.

The daily target idea has been tossed around a lot, but we figure it's a complexity we'd like to avoid in the interface if we can. The add-word frequency itself hasn't turned out to be as simple (or as well calibrated) as we'd liked, but we'll be working on making adding work better automatically. With a simple manual "add a word"-type button, that should go a long way.