I try to get onto every roof unless it is snow covered, or unsafe to do so. A lot can be seen on a roof that can not be seen from a ladder or through binoculars while standing on the street.
There are some attics that can be seen clearly from the hatch. Others that are large or have odd shapes are not so easily seen from that location. I think it's important to see as much of the attic as you can which includes looking for signs of animal activity; mold; structural issues; insulation and ventilation issues, and of course the roof. No roof inspection is complete without looking at the underside.
A common criticism and one seen and heard on television shows as well. It's sometimes difficult for home owners to remember the circumstances in the house at the time of the inspection. Was it snowing? Was there storage everywhere in the basement? The furnace couldn't be turned on because the A/C was operating?
Problems often become apparent when carpets are removed, when fixtures or cabinets are pulled out. Many issues appear once work begins on a home. A home inspection is a visual examination. We don't perform any invasive or destructive tests.