Yes, I'll agree with PGTips. You have to ask yourself what would be deemed reasonable by that bloke on the Clapham omnibus. Inspecting every square inch of the place seems over the top, especially if, after the first few hours, everything has appeared satisfactory. Inspecting nothing is negligent. So there has to be an acceptable middle way. Inspecting a sample of all relevant aspects of the building is the best way to conduct these. If the sample shows that there are some unsatisfactory elements then it would be reasonable to extend the sample. If everything in the sample is perfect then it would be reasonable to accept that the whole premises is satisfactory with respect to that element.
For example, if I'm inspecting a hotel with 200 bedrooms, I do not check every fire door. And I might lift a few ceiling tiles but if all is fine above those tiles then I extrapolate my findings to cover the whole premises. If everything is not fine, then that is where the fun starts and a recommendation might be to have a full survey carried out.