As I grasp the rules atm you complete a career when you have taken 10 points of xp in career specific advancements be they career skills, stat increase or so on.
Looking at the careers and mainly then at skills one quickly realizes one simple thing, you will never be able to train all the skills of a career before you leave it.
Lets say I start out as a gambler, the career skills available are Guile, Intuition, Observation, Skulduggery and stealth, all good skills.
The career advancements I am allowed for skills tell me I have to train one skill as one of the four fixed and then allowes me to train 2 more as open career advances, this would meen I can only train 3 skills as career advances.
For most chars this is fine as A) the skills are basic and you are allowed to use them anyways and B) moving on to a similar career will give you access to many of those skills at a later point my gambler is a case in point if he moves on to become a thief.
For the aprentice career its a bit different however.
Without channeling you cant use the channeling power meening you have a very limited number of power to fuel spells and without spellcraft you cant cast spells, even if you create your character with 4 skills and 2 specializations you will be very limited…
To me it seems you merely scratch the surface of the career before moving on, taking my gambler example from above I can easilly see me taking all my career advances as completely outside advancing my "gambler" say for example taking 1 reckless stance, advancing my agility to 5, a ranged action card, a talent a wound and the only real "gambler" advance beeing a skill from my list.
It seems like Im missing something it seems like, in theory an apprentice wizard could advance to become an acolyte without being able to read&write, channel or cast spells…