My parents are in a different country. Mil and Fil were in their late 60's early 70s when dh and I had children. Due to this even though they were 1 hours drive away when we first had children (now MIL is half hour) they have babysat 4 times. My oldest is 18
Once when dd1 was 14 months old and I went down with proper flu. MIL came and looked after DD1 for 2 days in a row simply feeding her and playing. Mil was exhausted literally grey in the face (and dd1 was a easy baby - MIL said this herself she was delightful)
2nd was when DD1 was about 2 MIl and FIL came and spend the afternoon with dd1 whilst dh and I (with baby dd2) went to a wedding for 5 hours.
3rd was when dd3 was sick one day and I had 1 thing I had to get done that day (I can't recall what it was but I can remember it was a time limited time so needed to be done that day) I drove dd3 down to MIl and she slept on MILS sofa for 5 hours
Final time was for dd2 one day where her primary school called to get me to collect her as she was very unwell with a cough. For some reason they could not get through on my phone. (no idea why as it was on and I had spoken to someone else about 2 mins prior to them phoning) So they phoned dh who phoned his mum and she collected dd2 and took her home.
DS has never been baby sat by in laws.
My parents are to far away to do any babysitting. So any level of babysitting we need has been done with close friends (love my then closest friend who took dd1 when dd2 was born and dd1 and 2 when ds was born and then agreed to take all 3 for when dd3 was due - however this didnt happen as dd3 arrived a bit quicker)
Reality is it has meant that dh and I rarely have gone out together, it is something we are now slowly working on bringing back. It has been interesting as the children grew to be teens (they all are this year) how this was a posibility again.
My worst experience of this was my having a V&D bug and dh was in America with business. I can remember throwing up into a bucket whilst standing in the kitchen cooking pasta and sauce for the children. (who somehow didn't catch the bug - I did clean my hands A LOT
)
Another time of my being sick with a stomach bug I can remember phoning for pizza and dd1 who was likely about 8 took it in when it arrived. the lounge looked like a bomb filled with pizza had exploded, however the children had got fed and I had managed a bit of rest.