So as I wait for my companion to finish the 25th combine on a green cybertech mod, I wonder why not make it so each RE attempt fills a bar for an item. When that bar is full, you learn the upgrade. You could still have the random chance to learn the new pattern at any RE attempt but it would limit the sometimes really crazy bad luck.
So a green to blue could be a max of 5 RE attempts, blue to purp 10 or something. Each RE attempt would either learn it or move you a bit closer to learning.