What I mean is you look at one then look at the other. It is two different predictive tools.
As an example...in my progressed chart right now my progressed 2/8 axis has been activated by pluto transits as well as the 2/8 axis progressing to sextile pluto and the natal MC is align with the 8 axis. In my solar return for this year the ruler of the solar chart, saturn is in the 8th house and the natal 10th is rising. Uranus in the second is heavily aspected and the ruler of the 8th is the sun.
In next years solar the 2/8 axis is the focus with 2nd natal house rising implying that this will play out even more.
The solar return has some inklings that 'yeah'someting is going on but I see when I look at progressions that there is an increased focus on the 2/8 axis.
there is a general rule of thumb that when an event 'occurs' ther should be at least three indicators such as progressions, solar return and your transits. This year Putlo, the ruler of my 8th, is rising to the top of the chart conjoining the MC. next year it will be exact. There is much more but I think you get the idea.