Matt the whole pole wants to fall into the wall, so all the weight is leaning that way.
It's all down to how much you scrub and rinse, slow and steady is the game, I use a flocked vikan at that height, I dont just leave it to chance.
In fact the windows at 6 storey came cleaner than all the ones below the 4th floor, I learnt i spent twice as long on windows above the 4th floor because of the slower movements, so it is all down to the time on the glass.