10 mile markers, 6 minute markers and drift lines for that matter serve no real practical purpose.
Have we forgotten that we essentially have a scale rule on every navigation chart? Remember that one minute of longitude measured along a parallel of latitude is equivalent to one nautical mile. Even an average student will be able to eyeball a distance with 15 minutes of practice. This eliminates the need for any type of marker. Markers are messy and can be very confusing when the aeroplanes actual speed is not what your planned speed is. They are also impossible to use in areas that are denied of suitable landmarks.
I think the best method is to simply mark your position and time every time you get a positive fix on your chart. On every leg you should calculate your revised groundspeed and work out a revised estimate. If you become disorientated or unsure of your position you can simply refer back to your last positive fix and based on your actual groundspeed work out a distance from that fix.
I personally don't believe that techniques should be taught if they can't be applied to faster aeroplane types.