How often to see MIL?

[Uptonogoodtoo]

Mil lives about 40 mins away. She is in her 70s but is fit and healthy for her age and drives. DH is an only child and we have three school age children. I’m never quite sure how regular the visits should be either mil coming here or going there. Any thoughts?
Obviously I’m referring to normal times, not at the moment.

I think every 2-3 weeks is fine. That's how often we see my inlaws (similar distance) who we both adore. Your dh can call between times to catch up if he likes.

Every 4-6 weeks!
That would be enough for me.
But my ExIL's lived 200+ miles away and I loved them dearly.
Does she have friends and social activities or is she completely on her own all the time?