Well for anybody, Shani (Sani) Dasa and its effects are good and bad. Look at my previous postings.
It runs for 19 years in a 120 years cycle. Maha Dasa. (starting from Moon - Vim)
Bhukthi is the total period of a planet in the MahaDasa - here it is 19/ (Dasa Period) for Sani / Shani about 19/120 of the time of Shani in your Bhukthi period. 798 days.
Anthra is the subdivision of the above and once again using the same principle as above, it works to 798 * 19/120 = 126 days, where super things happen in a person life.
So for a given Dasa and Bhuthkti and Anthra, the first period is itself. Lots of changes happen then based on the transit of the planet itself in various houses. Note that Sun and Moon period, always good results only in a given house - 12 you have. Venus gives a total changeover. Hmm.. Kethu and Rahu, are unpredictable. But it follows the pattern what its own predecessor does.
Here is the list with 120 as the period & percent of time ( Dasa/Bhukthi/Anthra ). Sort of the revolution time, around sun (but Parashara thought of keeping Earth Centric - thats why you dont see Earth in the 12!).
All the software using Swiss based Ephimeris DLL, take the starting point of the DOB and give you the chart for 120 years - assuming the max years a person can live is 120 only!