However, I believe my initial number was correct. I'm almost positive a tick is actually 3.33 seconds (3 ticks per 10 seconds).
Refresh 1 is 50 ticks of 3 mp, for a total gain of 150 mp, over 150 seconds. 150/5 => 3.
You may be thinking of hMP vs refresh while resting? I know refresh counts as 3.3 hMP when resting per 1 refresh. 10 seconds /tick after the initial 20 second rest. So a 1/tick refresh body (if you don't feel like changing to seer's tunic every hMP tic) beats seer's tunic because the 3.3 mp beats 1 mp over ten seconds. You obviously know this, but I'm thinking that's maybe where you got the 3.3 from?
Pergatory is correct.
Vana time does not compute down to 3 seconds exactly.
This can be easily documented with timestamp in game, or ask your favorite Samurai if they've ever received 120tp from meditate (72 subbed). 3 Seconds is simply the 'average' we use to simplify what SE insists on complicating to the extreme. That's why the Wiki refers to a 'standard tic' being 3 seconds. It's just the standard we've come to accept for the ease of calculations in reference to game time.