I wrote a long post on my phone then lost it!
I think it comes down to 'many ways to skin a cat', tbh.
There are lots of things that can be done in school, with minimal resources to have similar effect to the labour intensive therapies that are suggested.
So, take for example 'joint compression' - must be done every 2 hours.
What DD1's OT recommended were simple strategies to have similar effect:
-Stack some books in a corner of the class. Ask the child to help tidy them away. Bending, stretching, lifting, carrying - all gives feedback to the joints.
-Put some tins in a rucksack and encourage the child to wear it for short periods - proprioceptive feedback to the shoulders.
-a stretchy neoprene vest can be worn for short periods while doing 'sitting' activities. Gives feedback to the torso, which reduces fiddling.
-weighted lap pads and neck pads. I can make one for around 2.50, not expensive.
-What about star jumps instead of a trampoline?
There is lots that can be done in school, with minimal resources, which will do the same thing as the very expensive SIT.
I think it is very important to remember that the Law provides for every child to have an 'adequate' 'suitable' education, not Gold Standard.
Star makes a good point that 'if it works, does it matter if the evidence is there to explain why?' The short answer is no, unless you are asking a LA with limited funds to pay for it.
Only ask for a very expensive off-site therapy if a) you have lots of evidence that it works b) that evidence shows that it is the thing you are asking for that works, specifically c) your child can't learn without it and d) only that thing can work for your child.
Lots of ABA cases, for example, are turned down at tribunal, because while the parents can show that their child would make excellent progress with ABA, the LA can show that they would make 'adequate' progress with their intervention. The Law only insists on 'adequate' provision, so the Tribunal can't favour the 'excellent' provision of ABA, even if they think it is the best thing.