I always turn my indicators off as soon as I have completed my turn. False signals are dangerous. As far as I'm concerned, the fewer distractions a driver has, the better he can concentrate on the traffic conditions.
We've always been given basic advice - read some of the pamphlets dished out to housewives during WWII as examples but it is foolhardy to assume that just because something is 'basic' or 'obvious' everyone is aware of it.
If you watched TV in the 1970s you would assume that parents were incapable of teaching their children how to cross the road or protect them from 'stranger danger' (Charlie says.....)
Technology and gadgets may have caused us to lose some of the skills our parents and grandparents had (my mental arithmetic is dreadful thanks to calculators and google) but I have skills they didn't have.