Very reasonable. So with a five-day working-week, that's a six week long holiday, correct?
No, 5. Because your regular day off in a holiday week is accounted for as a "holiday" day.
What the heck? That's crazy. So you should always take your 30 days holiday piecemeal and avoid including any weekends in it, in order to maximize non-working time?
If it were me I would take my holiday Tues-Wed-Thurs for ten weeks, and then take Monday and Friday as sick days.. hmm. maybe 20 sick days would be too many.