Do you leave your kids with their Grandparents often?

I'm talking about for a few days in a week.

I've just find out the my brother leaves his 1 & 2 years with my mum for 3-4 nights a week. They also have a 4 years old. My 2 years old hardly gets to see her and now it's made it a lot harder. We hardly rely on her to look after her but on the odd times we want to it may prove to be difficult.