been doing an internal builders clean consisting of 80 windows of 2.4 wide and 1.8 deep , i haven't done a builders clean of this size before and ive noticed that when going back to check the windows they looked a bit smeared in places . any advice guys cause i seem to be going back and sometimes re doing them , is this normal or am i doing something wrong, initially they were filthy , plaster and pva which all needed to be scrapped off and just really grimey so washed all this off once with an applicator and scraper then removed all the dirt with a damp micro fibre and then squeegie off any suggestions would be appreciated