I've learned to compare our productivity to the schools, not to other HSers. It makes me feel better, since some HSers are way too organized for me! But I tend to look pretty good compared to a class of ND 2nd graders! LOL!
I think comparing yourself to other HSers is just too crazy-making. Are you doing the best you can do? Are your kids learning? Are they happy and growing intellectually and as human beings? Are they keeping up with/exceeding what their agemates are doing? Are they making at least a year's worth of progress for a year's worth of work (and hopefully/probably more!)?
Then you're doing fine.
HSing is NOT a good time to let your perfectionism out to play. It reminds me of grad school: you CAN always do more, but that doesn't mean you HAVE TO do more.
kcab: how about giving your DS fun games to play that require harder material. Let him choose: do this easy (boring) workbook or play this fun (challenging) game for school? Or are you doing that already?
