Here we have round boxes with ears like US old work boxes that are installed after the drywall is complete. So usually the drywallers are asked just to cut a small hole and leave thze flex conduit hanging out. After drywalling is complete the electrician returns, cuts in his boxes with a hole saw, puts in the boxes and installs the devices. On the last job the homeowner's dad was doing the drywalling. He asked one of the sparkies if he could cut the boxes so we only had to install them. Ok, he even lend him a hole saw.
Now when we returned we found he did cut the holes... but always only one, even where a 5 gang belongs... so we had big trouble finding the center of the round holes to mark the centers of the other boxes... *grrr*
My all time favourites are still tile guys who tile over electrical boxes! Had that twice. Makes for an interesting time!