I was younger than that when I was spending whole summers overseas with my grandparents, and I'm guessing with fewer phone calls than this kid got with Mom and Dad during her pandemic sojourn, and I'm really sure we all called it "visiting" and definitely not anything akin to "taking a turn raising the grandkids".

Though... my *other* grandmother did at least once try to trick my parents into giving up custody, so who knows what she might have called it if we'd visited her more often? (Three guesses as to why we didn't visit her more often, and the first two don't count.)