Juts recently this seems to be happening to me rather more. Is there supposed to some minimum delay? Has it been broken recently? Other's experience?

This is with a few hundred size 'to review' number, so no pressure from that direction. I've pretty much always had 'add characters from words' set.

Yeah, that happens a fair bit.

Can't say I have much of a problem with it though.

Our spacing algorithms aren't smart enough to say, "Okay, you just studied 中, so we need to push back 中国 and 中文 and 拔去眼中钉 a little so there isn't interference." So it's possible to get the characters first. If both are in the review queue together, there is some code that slightly benefits the longer words, so that you get those first.

But, I just realized, I recently made a change such that over 250%, the more-due items are actually done later, in order to focus on the more doable words. So the longer-word incentive would go the wrong way. Were the words you noticed this on above 250%?

I'll change it so that the bonus is applied after the 250% normalization, which should again give you the containing words first more often.