Paramathma says for the efforts we put in Sangamayuga we will get returns for 21 births or 2500, how far is it true.
We have to compare our kala to that of a mobile battery. In Raja Yoga each and every one tried to achieve 16 kala which is the highest. Like wise we charge our mobile over night to charge it to 100% . We know that the batter power stays for a long time meaning our battery to discharge from 100 to 90 may take say an hour or so, but a battery with just 30% power ischarges quickly.
Like wise an Athma with 16 kala takes 1250 years to become 14 kalas in Sathya yug. Likewise the same Athma which is 8 becomes 1 kala in 1250 years in Kaliyug.
The reason is that the usage of the mind is more in Kali yug than that in Sathya yug.