Answer

Yes, Chauvihar can be for a shorter period if it is taken as a personal vow after Pratikraman — for example, for 30 minutes — but traditionally, Chauvihar means complete renunciation of food and water from sunset until sunrise.

Explanation

In Jain practice:

• Chauvihar means not taking any food or water.
• It is usually observed after sunset until the next morning.
• If someone says, “I will do Chauvihar for 30 minutes after Pratikraman,” it is more like taking a limited personal niyam of not eating or drinking for that duration.

So, spiritually it is good, but technically the full traditional meaning of Chauvihar is not just 30 minutes; it is generally for the whole night.

Spiritual Understanding

The purpose of Chauvihar is to practice:

• Self-control
• Reduction of harm to living beings
• Discipline over taste and desire
• Purity after evening Pratikraman

Even a short niyam done sincerely is spiritually beneficial, but one should understand the difference between a small vow and traditional full Chauvihar.

Takeaway

A 30-minute restriction after Pratikraman is a good niyam, but traditional Chauvihar generally means no food or water from sunset until sunrise.