Commercial sheep are bred to grow fast, produce early, and die young!
We don't usually tup our Texel ewe lambs but have tupped a small number of very well grown Charollais crosses.
The incidence of problems amongst the hoggs is way higher than amongst the first-time shearlings, especially mastitis as the growing lambs make more and more demand on the young mother who is still not full grown herself. This seems to happen even when she is rearing a single (much preferred to twins, by us.)
Mules (Blue faced Leicester cross from a Swaledale or Blackface ewe) are often tupped as hoggs; we bought and tupped a batch last year.
We have also in the past bought Mule hoggs with lambs at foot. These sheep did not last very well at all.
I don't yet know how the Mules we bought as hoggs and tupped last year will last - they are looking good at the moment.