Establishing New Donkey Tail From Stem of Old Plant

I took two stems of a healthy donkey tail succulent and planted them into
cactus and succulent planting mix. The base of the stems and some parts of
the plant near the base appear to me to be unhealthy and shriveling. The
tip of the donkey tail looks healthy and is growing towards the light.
Here is a photo of the planting where it meets the soil:

Does anyone see anything here that suggests overwatering or a problem with
the planting?

Is some dieback near the stem base a typical pattern for this plant when
transplanted? I should be watering once a week? It's okay to leave the
stem totally dry six out of seven days?