It means that there is not a pattern available that facilitates long distance travel for your days on.
I did 8 days on / 6 days off, while working in Aberdeen which allowed flights to and from heathrow every week.
It is probably a fixed or flexi patten which would typically average around 4 days on / 3 days off, but may run random periods of days on and off which would make flights to and from Madrid for example frequent and expensive as there would be several rotations per month.
But if it is 2/3 hours drive each way that would be do able but then you have to pay for local accommodation as well as your main home.