The phrase "although not obligatory" is correct and usable in written English.
It can be used to indicate that something is optional or not required in a given context.
Example: "Participation in the survey is encouraged, although not obligatory."
Alternatives: "though not required" or "even if it's optional".
Intermittent fasting during the month of Ramadan, although not obligatory, is commonly practiced by Muslim children.
Although not obligatory, individual devotional prayers, especially during the night, are emphasized and are a common practice among pious Muslims.
Although not obligatory, its capped entry cards include services such as rail connections and are linked with an app giving real-time information on the numbers of visitors in each pastel-hued village – a subtle nudge to avoid bottlenecks.
Supererogatory acts in Urmson's sense (which is reminiscent of the Catholic doctrine) include only actions that are morally praiseworthy, valuable, although not obligatory in the sense that their omission is not blameworthy.
Although not obligatory for survival, it has been proven that the spleen plays a key role in mounting immune responses to antigens, and in the absence of the spleen, the body would be more susceptible to infections [ 36].
Although SMAD4 is not obligatory for TGF-β signaling, it is required to provide the highest response to signaling.
For every question, the children could nominate up to five classmates, although this was not obligatory.
Although participation was not obligatory, most of the workers chose to complete the questionnaire.
Although it is not obligatory, the examination is perceived as such by most women.
Most of the workers chose to complete the questionnaire, although participation was not obligatory.
Sacroiliitis is a characteristic feature of AS and is frequently found in patients with SpA, although it is not obligatory.
