These x3 events and (I don't recall we had too many x5) really helped to level a commander ladder, where the said ladder is tedious process and in my opinion is more hurting to the game population than fast progression.
The commander grinding process itself requires tons of boosts/insignias to burn. My observation was that as a subproduct of such 3-5 day quite grindy activity (per tier 10 PvE, to level one commander up to Colonel) a player can have reputation enough to pass to tier 8, maybe even to unlock tier 9 as well. Depends really on how much reputation bonuses were stacked together. There was some not so cheap XP-wise (Faraday) progression vehicles introduced last year and it just sunk there.
I do all recent levelings (like to K2) with Koenig, which is legit and efficient way to spend boost. I remind also its clone Sokolov was in open sale year ago and it is no longer "veteran with billion free XP" exclusive thing.