$50,000 is an average of $137 per day . . . say you play for 8 hours (including weekends) . . . then you need to make $17.13 per hour (roughly 3bb per hour) . . . if you play 3 tables that is 1bb per hour, per table . . . Play 6 tables and you only need to work for 4 hours instead of 8 . . . etc.

1bb/hr (per table) is a very reasonable win rate for 3/6, you just need to play sightly better than the average Joe at your table =)