The number of items you have to find is equal to the current level of your work.
>The number of items the player must find is equal to the current level of work. If the player breaks any item, they will earn the lowest compensation, but if they do not step on any item at all, they will earn a perfect compensation.
You can't make finding the items any easier, the player just look to the ground when there is an item nearby. You cannot use the Dowsing machine, and be careful not to step on the items.
>In the first three levels of work, an item will break if it is stepped on twice, but in the highest level, an item will break if it is stepped on once.
Note that while the Dowsing Machine cannot be used inside the building, the player character will look down to the floor if there is an item in the nearby area.
Since it doesn't say on any site if there's a specific place for the items, it's pretty safe to assume that they aren't in specific spots and are random.
Source
Hope I helped.
