These 3 Amp 7135 regulators are not so well behaved at the medium and low modes.
The 1 to 1.4 Amp max 7135 driver works better, but for maximum runtime and better regulation on medium and low, something like this is much better:
Shiningbeam used to sell these without the flashy modes as the ‘Perfect Regulator’.
Not much interest around here with the 1 Amp max but perfect for my long run time requirements. XM-L2 t6 still puts out 430+ lumen at 1 amp. Medium and low are well placed too.