Casual or sick leave, in general, is a benign and positive gesture of the employer in recognition of the employees' inability to be present for work lasting for a short duration due to certain unforeseen circumstances like sudden illness of self or family, discharging some social obligations such as attending a function in the family, marriage, funeral, certain personal works, and the like. Particularly, casual leave is subject to prior sanction or at least to prior intimation. For the sake of convenience of calculation as well as meeting work exigencies, it would be better to minimize its unit to a day or half a day, and not less than that.
Clubbing Leave with Weekly Off
Clubbing such short spells of leave with the weekly off or Sunday as a prefix or suffix, or both, is dependent on the type of your establishment as well as the Leave Policy of the establishment. For example, if yours is a shop or establishment that has a weekly closure day co-terminous with the weekly off of the particular employee taking leave, you cannot treat the intervening day of no work as an absent day.
Regards