My Hilleberg Akto packs down to 23" long. I place it sideways on the rack so I can also fit a sleeping bag and 1/2 a foam pad. It can also go lengthways when using a summer weight sleeping bag inside the pannier.
I have used a cheap Gelhert Solo which packs down smaller to 15 1/2". I can fit this inside my rear pannier (together with a sleeping bag) for summer camping.
You can separate the poles from the fabric, tie the poles to your racktop or top tube and stuff the fabric (dont roll it) into a smaller stuffsac.
Wet tents take up more volume so the Akto has a generous sized stuffsac.
People tour with tents of all shapes and sizes. A lighter and smaller packsize is better for travelling, a larger tent is nicer for camping. 24" packsize is really no problem.