Jupiter and it’s Mahadasha phase causes some fluctuations in life, just like Saturn for Jupiter picture is some different, since both are slow moving planets and their tenure in the form of Mahadasha and transit phase takes some long time compared to the other planets. During it’s Mahadasha phase some hardships and stiff conditions in life are possible because this is the time in which you will have sweet and sour experiences according to the Karmas.
Well it doesn’t means that if Jupiter is effective to your lfie in the form of Mahadasha then it will remain life long, since other factors which are supportive to the Jupiter will join in the form Antardasha, transit and Nakshtra Kaksha, thereby the experience of the results may vary in time due, similarly results will come to you based upon the favorable or unfavorable planetary association with the Jupiter.
Problems always appears big and enjoyments passes away in the short duration, how problems looks long! lets understand with the example. If you’re waiting for someone even minutes during the waiting appears like hours, same we can relate this situation with the problems, the phase of the problems looks like a big mountain.
On the other hand if you’re with someone who is your friend or lover the time passes like the clouds, why it happens? It’s a big difference between the enjoyments and sufferings even both occurs in the same time but the experience of the problems takes much long time, totally it depends on the mod and our capabilities that how we’re facing the problems and enjoying the moments.
Similarly the untoward effects generated during the Mahadasha phase of Jupiter, gets over but the overall phase demands to be alert and prepared for the testing situations which may or causing problems. Though the phase of Mahadasha will not remain permanently, like as problems are not granted foe the full life.
I hope this answers your concern