You should have a slight drag on all the drums. It is hard for us to understand whether what you call a "soft pedal" is due to air in the system, or just additional travel due to the shoes being too far away from the drums.
When the shoes are not dragging a little, there might be more pedal travel before engagement, but when it does engage, it should not be "soft" - it just has more travel.
Here is a link to a good video that explains that 4 point adjustment procedure for 39 - 41 brakes (the ones that have adjusters on the sides and bottoms of the backing plates).
https://www.youtube.com/watch?v=WxEwjnbfA2g&t=2s