You mean flascards? Doman suggests 5 in a row first, then another set next day, on the third day yet another set. On the fourth day you have 15 words this way. Each set 3 times.
But I do it my own way and it works
I suppose that it depends on the child. I do about 10 words in EK - it's words at the same time, because I use large font for the picture (word/picture) not just picture and tiny print that I read. That's because I usually can't get down to many session a day, so I do lots at a time. About 3-4 ppt (they ask for more, and are the same age as your children
)
Plus math - red dots.
BUT, when I do flashcards, it turns out that even 70 is not too much for them. Sure, who wants she/he turns away - for a while. They always (now) shout for more after we finish.