Not what my police driving instructor (note I wasnt police, this was private arrangement) taught me, which was to assess every other vehicle and whether they would benefit from me signalling. If nobody would, dont.The cars I've used with it will allow overtaking and lane changes as long as you indicate. You should be indicating if you will cross the centre line anyway.
The aim being to ingrain that constant assessement of all other vehicles and the massive safety benefits that generates.
Auto signalling is a terrible habit to have.
These systems also directly act against necessary emergency manouevres. They’re very much “not safe” in my mind and I have never really noticed any issue with I or others departing my/their lane that wasnt fatigue/drink related anyway where the vastly bigger problem is driving in that state.
I turn the things off immediately and refused a hire car where it couldnt be (or at least neither myself or the agent could work out how).