My tar shingle roof is sloped north-south.
Prevailing winds are easterly.

The paint under the north-east edge of the roof peels faster than anywhere
else.
This indicates that water is being pushed over the edge and trickles down
the trim and the brick on the east wall.
This is supported by the fact that the wood trim around the windows is
also being rotted away

I was thinking of nailing an L-shaped piece of metal or plastic along the
edge, to create a small barrier so that rain, on hitting the barrier, will
be guided down the roof slope to the gutters, instead of rolling over the
edge and running down the east wall.

Does this make sense ?
Is this a viable solution ?
What kind of L-shaped barrier should be used ?