Much as I look forward to spending time with my granddaughter each week, Thursdays can feel long.

I board the commuter train in my New Jersey town at 8:14 a.m., switch to the subway in Manhattan and reach my daughter’s apartment in Brooklyn by 10. Bartola, who’s nearly 3, comes hurtling down the hallway to greet me. (That’s a family nickname, a nod to the former Mets pitcher Bartolo Colon.)

My Bubbe Day shift (it’s Yiddish for grandma) lasts until 6. By the time her parents take over and I trek back home, roughly 12 hours have passed.

But that’s nothing compared to the time that Bill Borbely, 65, a retired marketing executive, puts in. When his daughter and son-in-law announced their first pregnancy, he recalled, “I said, ‘You don’t have to worry about day care.’ And they haven’t.”

He’s on the job Monday through Thursday in Point Pleasant, N.J., caring for two granddaughters, ages 5 and 3, for a total of 26.5 hours. Because I want Bartola to see that everyone shares in home tasks, she “helps” me unload the dishwasher and do her laundry. Mr. Borbely, however, has been known to mow his kids’ lawn.