Sleepovers at grandparents? Long post.

Okay so I myself am not a parent yet but my brother in law is (husbands brother). He has a toddler and an infant. Him and his wife let the toddler go to his paternal grandparents house every weekend. More often than not friday to sunday. This has been going on for about a 1.5+ years. Before during and after the infant was born grandma had the toddler for maybe 3 weeks straight. I feel like dad working a full time job he doesnt get but dinner and bedtime with the kid and weekends off. When I decide to have children I feel like they will be loved less because grandparents wont see my children 12 give or take days a month.

What I'm asking is it normal to have that much time spent at grandparents house?