The reference value for remote work is the total number of working days in a month. This means employees should also be able to work remotely for longer stretches (as long as this does not conflict with work duties).

Taking an average of 20 working days per month (five-day week), working remotely would therefore be possible on up to 12 days per month (whole days). These 12 days can be distributed over the month, i.e., employees could, for example, work remotely on up to 3 days each week or 12 days in a row (not counting weekend days in between).

In addition, you could work remotely on half-days. Using the aforementioned calculation (five-day week), you could, for example, work remotely half-days on all 20 days (calculated as up to 24 half days/month). 

A combination of full-day and half-day remote work (also alternating) would therefore be possible. Using the aforementioned calculation (five-day week), employees could, for example, work remotely for full days twice a week and work remotely half-days (by the hour) on two days. One working day would have to be spent entirely in-house.

All examples above assume, of course, that there is no conflict with work duties.