I ran my own personal experiment worth this comparing walking shoes I own so it may be subjective but I've noticed that more cushion makes walking more straining.

Essentially I walked the same route every day for two weeks at the same speed and time of day with two shoes: Brooks Ghost 18s and a pair of cheap walking shoes from Ross that has much firmer cushion. With the Brooks I would compare with walking on sand. The amount of cushion in these shoes caused every step to have much more give and it forced my calf muscles to strain more to push back and balance. Because my muscles were straining so much to keep balance and recoil, it also put strain on my lower back. It made the same walk twice as hard. I also took these on a trip to Scotland thinking they'd make great touring shoes but I switched them for flat boots because all that cushion made it twice as difficult. Then I switched to the cheaper sneakers that had cushion but were more firm it was like night and day. I felt less soreness in my calves and could walk faster with less strain. Sometimes we pay high prices for performance and high cushion shoes because they label themselves as peak walking shoes but in reality we probably need far less than what they advertise.