yes, cushions are really important in shiatsu practice.
I have several cushions which I value for shape and size, texture of filling, and texture of the cover. Generally natural fibres are good.
And then there is expertise in cushion management - a well kicked cushion can move into just the right place - either out of the way, or ready to support eg under the knees.
Sometimes people suggest that I don't need to bring my own cushions; they have pillows / cushions I can use. But I always find I miss my own cushions if I follow this suggestion. Some pillows are just reluctant to move, and of course I'm not familiar with them, and how they will respond.
Next time, I'll write about blanket expertise - a whole other, though actually similar :-) topic.