If sheep have hard or stoney ground to walk over they can keep their feet worn down without the need for frequent trimming. However, if you have only wet pasture for them, then any breed can get bad or overgrown feet, in particular with the outer edge folding over and trapping soil underneath, which will lead to anaerobic bacteria being trapped and multiplying, and causing rot.
Some breeds though, which includes Soay, have a tendency to have fewer problems than other breeds. Black hoof often seems to have fewer problems than white. Jacob hooves are usually dark, but sometimes have white stripes in.
'Good' feet seem to be heritable - we include foot quality in our criteria for keeping both ewes and tups, and in the 'lines' we have developed (along with long-keeping teeth and a whole lot of other factors)
We check our sheep's hooves frequently - whenever we have them in for anything, but if they don't need any trimming then we leave them alone, certainly we don't trim them just because we are looking. By checking though we make sure there are no problems, rather than just ignoring them altogether. Our other strategy is to bring in an individual sheep if it is limping for a day or two and inspect the foot.