I used mostly indirect on these. About 80%.
Very little direct percussion to rough out the initial biface. Then lots of flake removals with a small indirect tool... so I wouldn't take too much off when thinning.
Then pressure retouch to clean up the edge just before the final pass followed by lots of grinding and more retouching and more grinding until the edge is just about as perfect as I can get it.
Then very careful indirect for the final pass.
Easy peazy.