I consider ourselves pretty lucky that dd in 1st has less than 5 min. of homework (yes, that is how long it takes her to do the Everyday Math worksheet). And dd usually only 10 min. or less, just depends on how much she is struggling with it. So I don't see a problem with adding a little extra to help dd#1 where she is struggling, and a little enrichment for dd#2 to challenge her a bit.