Simbo,
Firstly, if you post a question - read it!
If some is missing, then edit it immediately ('Modify' button) until it reads correctly, otherwise we will waste time answering a question that was not intended to be asked.
If this care home is anything like the ones I do, do not expect to do even just the 20 bedrooms in 16 hours.
The machine MUST be left outside the building, otherwise the urine odour emitted from the machines' exhaust will stink out the entire building.
Since the consequences of a trip are likely to be more severe to the elderly residents, the risk needs to be limited by careful placement of hoses and cables. This results in frequent re-siting of equipment which increases the slack time of the job. Many of the homes that I do could be covered with the machine left in one position, running 150' - 300' of hose but this would entail too great a risk, with hoses crossing too many traffic lanes.
Moving ancillary equipment such as blowers, Host machine, sprayers etc., re-locating hoses, often with several trips up and down stairs and along corridors can take up considerable time. Often the ideal route is not possible because certain doors and windows cannot be opened because of draughts.All these factors conspire to reduce cleaning efficiency. Time can also be wasted at certain times of day as hoses may need to be moved as the residents are moved within the building at meal times, bath-time etc..
Most of the bedrooms are likely to be small, containing a minimum of bed, bedside cabinet, commode, armchair, chest of drawers and wardrobe, plus a collection of personal nick-knacks. consequently you can spend as much time shuffling furniture as you spend cleaning.
When costing the job you also need to allow for increased chemical costs due to the use of urine neutralisers, sterilisers etc. and the need to sterilise your equipment at the end of each cession.
The above is as true for both truck-mounted or portable equipment.