In my view 5 day working in a week for any production unit/factory is not possible. How do you manage the furnaces run round the clock without manning it or many unavoidable things & processes are existing in a factory that require manning round the clock, to resume production after holiday. Though it sounds good but not a SOUND idea.
The cap fixed on the total no of working hours for a worker in a week u/s 51 of the Factories Act,1948 limits the no of his working hours per day automatically. It implies that the average working hours per day can not be 9 hours but only 8 hours. So the 9 hours a day fixed u/s 54 is the maximum limit constituting a day's normal working hours. Your proposal of switching over to " work of 5 days week " may be more beneficial to the workmen in respect of weekly off or weekly holidays but such benefit can not run counter to the explicit provisions of sections 51 and 54 respectively by fixing the normal working hours at 9.5 hrs a day.