It’s really great to see you thinking so deeply about who your end users might be and ensuring that your design is appropriate for them! I’ll try to answer your queries with as much information as I can.
In general, it is most likely that women in Cape York are taking on the majority of the washing and therefore will likely be the main user of your design.
With that in mind, as outlined in my previous response, the roles and responsibilities of women vary throughout the Cape York context, and therefore we are unable to definitively say how much time is available for housework vs employment as there is not one ‘average user’ per se. I recommend taking a look at the 2016 census data for Cape York (linked in the ‘Tips for Getting Started’ page) which will give you an insight into the demographic make up of Cape York, including percentages of people working, the hours spent doing unpaid labour (eg housework), household composition etc. which can help frame your system users.
With that in mind, it would be worth designing your system so that it is appropriate for a variety of users, including those who may be working. I would also challenge your assumption that if a user is not in paid employment then a less efficient model might be suitable – as unpaid labour disproportionately falls onto women, a more time consuming washing process may add to their burden and could discourage uptake.
Ultimately there’s likely to be some trade-offs in your design that you will have to weigh up, decide on and justify in your report. For example, if you have a system which is less time-efficient but is cheaper for your end user you may decide that trade-off is justifiable.
I hope this helps to clarify some of your queries and assumptions!