Will it work on all sps? No. Some species do not react in the same way.
Does the size matter? Yes. The sps must be a colony size and growing (pool ball was a good one). If the entire coral is stagnant and not growing, this will not benefit you and will only hurt the Coral. the sps corals must be healthy and growing. It’s not a magic trick to help you grow corals if you’re not successful at growing them to begin with.
Does this have any effect on the growth rate of the new frag? In my experience, not at all. This technique, if you even really want to call a technique, only benefits the colony where the cut was taken, not the new frag.
Does the size of frag matter? In my case; absolutely. When I take normal/larger size frags, I notice that multiple branches will grow back, while when I take nub sizes, they don’t typically grow back with multiple branches. I’m not sure how the razor score will work, my guess is it will not inhibit new branches.
I’ll take a photo of one of my more recent examples of this when my lights turn on.
This RR Aussie gold is a perfect example of what it will initially look like one week after fraging. What is happening; when you frag a branch, it stunts the growth and gives the opportunity for the next branches to catch up and surpass the original spot where the first frag was taken. It essentially allows for everything to grow at the same pace, once the Coral is healed, if that makes sense? The red circles are where I cut frag’s, and you can see that there are now going to be multiple branches in one spot.
The rest of these are examples of what they will look like after a month or two of healing and growing. As you can see, these next photos are prime examples proving it is a fact that cutting branches will help initiate new growth at that location. It’s similar to cropping plants for more branches.
I think an interesting follow-up to this, if confirmed, would be to selectively trim for desirable growth patterns. It would be cool to have a "bonsai-esque" segment of the community that not only keeps beautiful SPS but also grows/manipulates them into specific shapes and growth patterns.
I have definitely observed this phenomenon in my own tanks after "accidental" fragging with my big clumsy hands haha. Growth on the accidentally clipped colonies clearly accelerated on those affected branches.
I believe growth pattern is dependant on the zoanthely. Almost like nomadic farmers, the polyps follow their crop. The zoanthely are plant based and cause the coral to grow towards the light source. If this is the case then cutting a coral or forceable stunting or halting growth would be like a plant sprout finding its way through a crack in a side walk. Since it was denied growth in one direction the coral will seek alternate routes.
This has been a known standard proceedure for 20+ years. We don't need to study it anymore. It just works. We used to cross slice acro tips way back in the day on stalled growth. I think todays tanks are generally more healthy and I have not needed to do this for many years. The branches just grow until they hit something or grow out of water.
On new frags let it get a good base going and then cut the original frag half way or so up and you will soon have a mini colony starting.