make the transition from level 6 to 12 interesting

At level 6, we unlock mechanic, it's a great moment!, But we can not win as much XP as before with this job, at level 12, finally unblocks new jobs, 3 to be exact: paramedic, truck driver and fisherman. Why not put one of the 2 type "XP farmer" (fisherman or Tank Driver) at an intermediate level for example, at level 9, to leave the previous trades faster (to evolve, we have to play farmer, hunter , pizza delivery and bus driver for a long time). It would be more fun to make the transition from level 6 to 12 more fun with nine or one of these 2 jobs. Another argument, at level 12, we evolve quickly, so quickly that the players use only 2 trades of this level on average (paramedic and truck driver), the third fisherman is so little played that 3/4 of the police (that I met) do not even know the starting point for this job.