Exactly my experience, too. Plus as our soil is *really* clayey, it is hard work to pull them out of the ground.I’ve got a set and I wouldn’t recommend them for the reasons of when the soil is damp you can end up with big clumps of soil stuck in between the spikes.
Also the straps are not that great and come loose easily. My dad has some as well and glued some old shoes to the top of them to get around this problem.
I use a garden fork instead now, it takes a bit longer and is harder going, but I feel gets better results.
I read that brushing dry sand into the holes is a good approach if your soil is heavy/clay. The worms distribute it, improving the soil quality over time so you then don't needc to aerate so often.