Just letting players know I recently updated the teaching code (player to player), so if your brains fall apart, you know who to blame.
Player to player teaching makes use of the neural transmitters available for sale in the Pyramid electronics stall. It requires a skill level of 20% or higher to use.
It has been updated to give more experience, and if the student fully passes, he/she will now gain 1% in skill. If you do gain this 1% increase in skill, you cannot train via player to player for 7 days in that specific skill (your brain needs to rest up).
The odds of passing a lesson improves if your teacher is highly skilled, and it becomes harder to pass the higher your own skill level is. And once you reach 50% or higher in a skill, you will need to rely just on CNPC lessons to level up. You can gain experience (just not skill raises) via player to player lessons, regardless of how high your skill may be.