Driver Training Signs
Most areas have local laws determining what kind of signs, their size, where they are to be displayed and what the colour shall be for on road training. In addition to placement, exact wording is often specified by your Motor Vehicle Department. Check local laws for information for your area.
Most motorists tend to ignore these signs even when they see them on cars which often display "Student Driver". This is not good.
These are important advisory signs.
Any sign which indicates Driver Training, Student Driver or displays some similar message is very important. This tells other drivers that the operator of this vehicle is learning how to operate it successfully. Therefore it's operator may make mistakes. It may not go in the direction the signals indicate. It may not be in the correct lane when it turns. It make take more space than usual. It may stop or turn suddenly. You get the picture.
Of course it is the instructor's responsibility to be monitoring driver activities at all times to ensure all rules are being followed and that the vehicle is being manoeuvered safely.
It does little good to get frustrated if they are going too slow. Don't get upset if the operator takes longer than necessary to make a left turn. Give them some extra space just in case. Be patient, after all, we all learned to drive at one time, and I doubt anyone did it 100% correct the first time at an ordinary speed.