Already tried to embody the idea - in fact it turns out the same as now. Unless you have to take breaks more often, or less often, depending on the specific numbers you balance.
Stamina builds up over time and then instantly turns into an item. Or we wait, after pressing the craft button, in the standby mode in the city (possibly a castle, or a village, if you craft through the menu with the possibility of waiting)).
If you want to see a working idea, you need a unique craft. Otherwise, the game turns into a waiting simulator. Or charged companions and fight, again waiting.
According to the mind, you need to add a mini-game, such as targeted attacks on the anvil, as on the enemy, so as not to be smart with the mechanics and balance once again.
Quite rudely, remember the "Warband".
I did it there through the training camp. Newbie craft - fight with a newbie. Craft top equipment - fight with four best fighters at the same time.
Battle-Training, when you win, we get an item. No - you can cancel (return materials), or try again