I forced myself to use one finger only a few years ago now.

Moving the levers in so you can only get one finger to reach the lever definitely helps.
Also as you are pulling on the very end of the lever you have better leverage so less power from the finger is required.

It felt weird at first but I just consciously made myself only use the one finger. After a couple for weeks it felt natural.

I’ve just fitted a pair of slx disks on my bike today and just got back from a shake down ride. It was a bit daunting to start with but towards the end it felt quite natural to 1 finger brake.

I brake with the middle finger.

My 8yr old son uses one finger braking…he regularly crashes too.

However the one finger braking has nothing to do with the above. Once you are used to it it’s fine.