Personally i often want to block out hard edge areas of color and without selections or masks I use the paint roller to do this... I also use the paint roller to go over and hide the uniform rough striated 'broken' edge that is at the start and end of marks made with the square tip oil brush. Having insta-dry on the roller would give me a hard-edged taped or stencil look i would greatly appreciate if it were ever to be an option.Thanks