Goats and sheep are similar, but very different in many ways. One being in their hooves. They grow and wear much differently. 

   I have found that sheep hooves are softer than goats and wear much better most times, usually requiring less frequent trims. Which absolutely makes sense as sheep are grazers, traveling on soft ground in fields of grass and weeds. The shape of  their hooves are very similar but due to being softer, tend to show less over-growth of hoof wall and heel bulb. They will get some flaps at times if the area is often wet and muddy. If you have problems with wet or muddy ground, you may need to have them done more frequently. Also be sure to watch the carb/sugar intake on these animals. Being they are grazers, they don't naturally search out whole grains as feed. They will metabolize these whole grains differently. Corn in large amounts especially, will cause major hoof problems and expose the animals to problems with hoof rot and laminitis. I saw it in a herd of 30+ sheep and it was quite awful. They were newly purchased from Montana only a few months prior, and now living in Western soggy Washington. They were being fed large amounts of whole corn and alfalfa hay. This coupled with the wet and rainy ground, created huge problems with hoofrot AND laminitis. The owners felt awful and did what they could to prevent the sheep from living on mud. 

   Goats hooves are much harder as they are primarily browsers. They search up high for their feed sources and often times are climbing on rocks and logs, wearing down their hooves on these hard and rough objects. A lot of goat owners don't provide these kind of obstacles for their goats to climb on, therefore the hooves tend to grow long and the wall folds under the hoof. This creates the perfect dwelling place for dirt and debris and perfect breeding ground for anaerobic bacteria which can lead to infections and hoof rot. Goats also suffer from nutrition based laminitis. They primarily do not rely on whole grains as part of their diet, but being domesticated, they are heavily supplemented with grains. Some more than others. I have seen through the different herds I've visited and trimmed, each goat is very different and metabolize the grains different. Within the same herd, some goats feet were fine but others showed signs of the inflammation within the capsule. Acute laminitis episodes are easier to treat, usually by cutting out grains immediately and introducing more forage sources. Trimming the hoof and making the goat more comfortable. Chronic laminitis is not quite as easy to treat and can take a longer period of time to treat with trimming, adding pads and cutting out grains. One claw may appear to be much larger than the other. This is often the affected(laminitic) claw. The best option is to trim as short as it is safe to trim, and block/pad the smaller claw. This elevates the affected claw off the ground, taking pressure off of that claw and hopefully creating a more comfortable animal and promoting healthy hoof growth.   

   When trimming goats and sheep, you trim to make the hairline(coronet band) parallel to the ground. The bone structure on goats and sheep are very upright, so when trimmed, the hooves will resemble a square in shape when viewed laterally. This usually means I will trim the toe(which often grows quite fast when not worn down naturally) and will level the heel as needed. Once the feet are balanced over as many trims as it takes, I will not need to take much or any sole from the goat. Just a simple wall trim and quick rasp to level everything out and the hoof is good to go! 
   Frequency is very dependent on a few factors. Current hoof condition, the ground type, the activity level of the animal, and whether or not they have and use climbing toys. Some goats who live on softer ground, may be less active or choose to just be flat lazy, tend to need more frequent hoof trims. Starting at every 4 weeks, going to some only needing it once a year to simply balance the hoof. These animals tend to live on hard ground, are active and may use climbing obstacles.  

    One thing you can do to really help your animals, especially goats, is to give them a rough surface to walk on. Adding stumps and large rocks for them to climb on, adding elevated areas of walkway to keep them off the ground of muddy(such as pallets with the slats covered to prevent a caught hoof/leg) and use  a shingle type of rough material to cover. This adds grip and wears hooves down. I love using the asphalt sheeting for added grip and wearing down excess hoof wall. Put it on top of spools, stairs, on the rooves of any small goat houses. Basically anywear your goats may frequent.