This model guides to a period of 25771 years until the vernal point returns to its initial point. But this number can be wrong if the motion of the vernal point has long term fluctuations. Such an effect may be caused by unknown galatical phenomenons or fluctuations in gravitational fields.
Standard configuration of custom Ayanamsa is based upon a reference value at a given date (normally Jan 01 1990 = 2415020.5).
According to the Holy Science the period for the movement of the vernal point is 24,000 years.
Sri Yukteswarji combines the movement of the vernal point with the theory of the Yugas. According to his view Kali Yuga's duration is 2400 years (ascending and descending each 1200), and the start of ascending Kali Yuga begins when the vernal point is 0 Aries. Dwapara Yuga follows and has double duration, each Treta Yuga has 3600 years and each Satya Yuga 4800 years.
Therefore we have the sequence of Yugas shown in the table below.
|Yuga||Duration (Years)||Vernal Point (Start)||Vernal Point (End)|
|Kali (ascending)||1200||00 Aries||12 Pisces|
|Dwapara (ascending)||2400||12 Pisces||06 Aquarius|
|Treta (ascending)||3600||06 Aquarius||18 Scorpio|
|Satya (ascending)||4800||18 Scorpio||00 Libra|
|Satya (descending)||4800||00 Libra||18 Cancer|
|Treta (descending)||3600||18 Cancer||24 Taurus|
|Dwapara (descending)||2400||24 Taurus||18 Aries|
|Kali (descending)||1200||18 Aries||00 Aries|
Disadvantage of this method is that long term predictions are not correct because the period is wrong.
Disadvantage of the method is that the actual true movement of the vernal point is neglected.
The current precession is too slow to get a period of 24,000 years. So it must be near a minimum. The speed must grow in later periods to get the desired total period.
Possible positions for the minimum could be the point 0 Aries or the point in opposite to the supergalactic center (i.e. around 26 Pisces).
Investigations regarding long term Ayanamsa can be made taking old sources that rely on chitra paksha (i.e. Lahiri) ayanamsa. Most contemporary authors do not rely on old sources and pretend that they are not correctly calculated.