I have been struggling to hoe effectively without going too deep, thought it was me. Since it was also giving me a stiff back I decided to buy a longer handle and hey presto not only do I now have a less stiff back but the hoe is at a much better angle and so only moves a little soil.
It had simply not occurred to me that the length of handle was so important.
For the record I have a dutch hoe and the handle is now approximately the same as my height ( 5’7″)
Hope that this is of help to someone.