I'm not entirely sure of my play time per 60 but I didn't take my 3rd 60 very seriously and honestly, spent a lot of time AFK. Still did 1-55 in like 12hrs (12xp). You can knock our Rishi/Yavin/Ziost in a night though so 20hrs if you are taking your time seems about right.
<Empire of Korriban> an RP/PVE guild is now recruiting all levels and experience. We have a Stronghold, Guild Bank, 10% XP buff and Website. Whisper any member online for an invite or visit EmpireofKorriban.com for more info!