I lingq every word. But, instead of doing SRS in the form of flashcards, I do it by repeating lessons. This seems to work well when the content is 20-30% new words when I first start working with it. If it has more new words then it becomes an exercise in deciphering too many sentences. However, if it has fewer then it quickly becomes boring to relisten to it. I use the same lesson over the course of a few days, and when I get bored with it, I move on to a new lesson. I've been doing about 30 minutes' worth of audio at a time. Occasionally, I go back and review lessons I've done in the past but haven't looked at for a while.

It achieves a similar effect as SRS, at least I think it does, without having to suffer through flashcards.

Don't think there's no right amount. Too many variables but the more, the better for efficiency to create progress.

You can lingq every word except names and lingq sentences to get better reading comprehension.