In the UK I’ve tended to signal moving out to overtake, but not always when moving back into the previous lane, especially if no one else except the overtaken vehicle was nearby.
It was doing that in Spain that made me aware this was a feature in modern cars.
I encountered this on a hire car in Spain. Unless you indicated both ways on the motorway it would object whenever I tried to pull back in after overtaking. That was a bit annoying, but other than that I thought it was an ok feature and hardly noticeable 99% of the time.