Rather than increasing the experience requirement when switching jobs, wouldn’t it be better if you lost half the experience of your old job when you switch to the new one?
This would prevent abuse of this feature and still be somewhat forgiving of mistakes. This way each hearthling would learn just as fast as a new hearthling, opposed to what it is currently where it could take you 3 times longer to level up after switching jobs.
I would rather lose the experience of a job I might not ever want to switch back to and restore the leveling speed to normal than have one hearthling that eventually masters all jobs in the game- its just not as likely to happen. I don’t think this would be unreasonable for vanilla stonehearth.