Boost for no reason.
When I'm counting for my own benefit and the number is in the range 0-10, 1-5 are right-little to right-thumb, and 6-10 are left-thumb to left-little. I am right-handed.
If I'm emphasizing numbers while talking, 1-5 is right-thumb to right-little, and 6-10 is again left-thumb to left-little.
I'm not sure it's particularly interesting or useful in itself.
I think my behaviour is affected by multiple things:
Expected number of items - if I know it will be in the range 1-3, I would emphasise the numbers from index to ring finger rather than from thumb.
Physical feedback - I think the reason I start with my little finger when truly counting is that I snap the fingers out from under my thumb which reinforces the sense of moving to a new state.
Social context - probably overrides all else.