Thx Nikosthefan for these questions.
All ideas beneath are just my analysis and therefor pure subjectivity.
The first idea was just “number game” as you said.
Conversation and Mentor
I didn’t thought that conversations would be introduce in the process at first place. To be honest, I don’t know how it could be introduce smoothly into the gameplay.
Indicating that exp/bonus is linked to speech seems a bit odd because you can’t control the conversations of your hearthlings. You can’t use and prepare strategy this way. For example if you want to fast train an hearthling, the mentor is busy working and don’t want to pause the work to teach the mentoree or the conversation is never about chairs yours bonus time is totally unreliable.
When 2 crafters have different levels
the lowest level get a bonus (based on the level difference for example). Each crafter keep their habilites and this could be tweeked by a limit on a maximum level to apply this bonus (when all “first aid” craft are unlocked the bonus is no longer applied) <= this limit level has to be discussed to balance and stabilize the game.
the highest level get a minor penalty to sustain the mentoree/simulate the time spend on mentoring. This will slow down his progression.
This add another gameplay element. The player will have to wisely choose the moment he want some hearthling to level up or not and he will have to manage the 2 workers 1 job situations. Thus it might be a good idea to invest time in blueprints and books.
Craftplans and Books
Craftplans and Books is a new Item create by the crafter (so it can be sold and buy). This can unlock the items to be craft at the level the book or blueprint is draw. This way a level 1 carpenter can craft level 3 items.
This can be used in situation you want to change jobs affectations but you don’t have enough heartlings or your only carpenter died. You don’t have to “farm” stockpiles or other cumbersome items to level up your new crafter.
But of course this have to introduce penalty on crafting time if the item crafted is on a level higher than the crafter level.
With theses new elements the player could now have interest on a “2 workers 1 job” play to boost production or train most crafter in one time than successive trainning. Or the player can just backup and simplify/steady the production by creating books. Without mention that these items can have value (knowledge is priceless ).
Hope it has answered your questions and sprout up new one hence new ideas.