The master bedroom gets changed 2X a week, the big kids, aka potty trained usually on saturday, unless something requires it more often, usually DD like to craft on the bed and little pcs of paper, glue, beads etc make for new sheets etc.... the littles are almost daily due to diaper blow outs, spit up, baby issues still... 8 kids mean there are 9 beds to change counting the master... thats a whole lotta sheets, blankets, etc.... dont even get me started when the flu is going around...
FYI, we have standard crib sheets and twin sheets, the master is king... the kids are way over having thier own sheet sets, we buy pretty blankets for the kids and sheets are whatever they grab...