Would have to be a very limited periodic inspection on all 6 houses to do them in that time,it takes as long as it takes for you to give your professional opinion on the condition of the existing wiring and accessories,it gets right up my nose when GUVNORS decide it will only take 2 hours per house,what exactly do they expect to be done in this time scale,what he is really saying is im being paid for 6 houses and you must get it done in that time,fill that limitation box on anything you cant fit in the timescale,dont really see the point in a squeezed periodic,personally i would want to take my time on it,do it correctly and be happy signing satisfactory on the report,if indeed it was satisafactory.