Hello Svaever,
In Enugu we are flying 3 r66 and some agusta 109.
The r66's fly pretty much all day monday to friday.
Generally helicopters set the transponder on ALT just before pickup and then we never change it. I believe this is normal procedure everywhere for helicopters due to the high workload for the single pilot when hovering.
I remember when flying in the US I always left the transponder on ALT even in busy airports like Seattle or Portland.