At the beginning of the apprenticeship, apprentices cannot do any work at all. As workforce, they can be considered "below zero." However, doing the chores is one way to contribute, which actually teaches many important things.
Materials shrine & temple carpenters handle are very expensive. One piece of pillar can cost as much as a luxury car. It only takes a moment to mess up, but there goes a luxury car because of such failure. We work under a tremendous amount of pressure. That's exactly the reason why apprentices may not do actual work as they cannot be completely trusted. We thus have a chore called "pre-work." Apprentices are tested at all times to check if they can finish their chores responsibly. If they do a sloppy cleaning job, it will be assumed that they work sloppily, too. Conversely, an apprentice will be very much trusted if she/he cleans neatly and efficiently. No, it’s not only about making things cleaner.
Apprentices also cook meals for those who train them. Making meals is a part of "pre-work." Preparing for meals is exactly the same as planning and arranging for their own work. In other words, those who cannot make good plans and arrangements for making meals are not good at planning for work. Those who prepare well for meals and cook great dishes, on the other hand, can of course plan well and do great work.
It has been said since the ancient times that perfection is made of 80% preparation … which means good work is 80% determined, based on whether the preparation was well done or not. They are thus learning about work preparation through meal preparation.
We have extracted great aspects of the apprentice system and turned it into a new training method that matches the modern times. This is how we train young shrine & temple carpenters.