Was that with 300 tp?
How did you gain 100tp in 20 seconds? (would require ~69% haste ignoring shield/store tp)
How did you do 70-72 in 15 hours with a 20second fight time (~70k/15hr = ~4.7k/hr. Even if you were getting 150xp a mob, 20 second deaths would be 25k/hr+)
As far as haste/store TP goes, I have a Euphoria Ring that gives me +1 Store TP (working on Chivarous). I usually ask the healer for Haste to speed up my attacks since I'm using Joyeuse. If I double-attack every swing, which happened alot, then I do get 100 TP in under 20 seconds, in which the SAM friend and I do Darkness SC as fast as possible to avoid Amniesa from the Imps. Of course, it happened sometimes, so not every fight was under 20 seconds.
I would've expected alot more exp from my party, but not everything was perfect. There were some problems, such as competition which didn't allow us to pull as quickly, and when I hit 71, we moved to Puks and Mamools, which turned out to be a bad idea since Imps gave more EXP and Mamools are asses, which caused me to die twice there. Also, at a point we had a JP bard, who wasn't a very good puller, and often worried about our WHM's MP. It wasn't until we eventually repped our brd (had to leave) with RDM, then repped our WHM (disconnected) with a SCH, then moved to Nyzul Isle's Caedevra Mire for Imps, that we were really getting quick and fast EXP, and that was when we were at the 13 hour mark. So basically our pulls were too slow, and we just never had the chance to get into a groove.