My mother was a terrifying juggernaut of doom at Dutch Blitz, which we tended to play in 5-7 person clusters. But at least when it was just family, we tended to deal with that by having actual handicapping. Since you need to run through your stack of cards, my mom would take a few extra cards in the stack, and the youngest kids would take a few less, to give them a fighting chance. (Since my mom comes from a family of golfers, it made perfect sense to have a formal handicap.) So no one felt completely curbstomped, but it was also a point of pride to be able to work up to using the standard number of cards.