A motorcycle mechanic at a dealership told me that the R3 engines really don't need valve adjustment since these engines never hit extreme sustained RPMs.... with that said I had mine adjusted at 10k miles.
Afterwords the tech told me that I had one valve out and it was very small on top of that. I felt like I should have took my money and burned it.... would have gotten more out of it.
This was back when Triumph recommended the adjustment at 10k rather than the newer 20k.