There's not much point in getting into this science versus magic argument. I doubt we'll agree.
However, let's keep this factual. The normal course of orf in any animal is ONE WEEK in the vast majority of cases. This is well known, and well established by trials, and in field outbreaks. For centuries. If your sheep had a similar skin condition that lasted three weeks, it was something else. An outbreak can go on for whatever length, as animals pick up infections, but each individual clears up in a week, unless they get something else.
If you believe in magic and it works for you, good luck. In fairness, science doesn't offer much in the treatment of orf. Neither does magic.
If anyone could really cure it, they would be on the road to wealth.
Your argument appears unresearched. Do you keep lambs or are you just giving your opinion?
Before chemicals were available, farmers used people with cures for to treat most illnesses in animals. Just because you don't know anyone who uses these does not mean that they are "Black magic" or anything to be made a joke of like you did above. In reality you are making the joke of your own ignorance to cures.
Secondly, Blue Stone and washing soda are not harsh chemicals. Blue Stone has been used for hundreds of years to dose cattle and sheep for fluke, to treat foot rot and to treat orf. It is an organic treatment and does not have a meat withdrawal period. Washing soda kills germs - its anti-bacterial and has been used for this purpose for many years before dettol or savlon were produced.
Also, there has been some extensve research done on orf in lambs in the uk. They claim that the normal course of Orf in Lambs is SEVEN to TEN WEEKS. Maybe our lambs are more immune than theirs, but I really doubt it.
References are here: