The experience bonus is enough after your first level 50 that subsequence gained it much faster. Almost each time I ran a dungeon I'd gain two levels. I remember thinking one thing was holding me back from zooming to 50: DF queues as DPS. So I'd suggest looking for at least 1 healer or tank who wants to do the same, and queue for a string of dungeons with then, taking breaks for job quests burnout etc.