They really do come into their own when negotiating gates.
I find a rein back is easy if opening a gate towards us - then adding a quarter or half turn on the forehand to close the gate once through it. Try & practice - and try not to let go of the gate all the time you are doing it.... takes practice but you can make it look so easy when you can do it properly.
If you know the aids & are able to do the movements in a school area then you can apply this anywhere but as I mention above, they are most useful when doing gates.
Like leg yielding - this is helpful in traffic id horse has moved out into the road a little - just leg yield back again.