Promoting small portions and half portions can increase time and labor and material costs to a certain extent, as additional processes are required for preparation and sorting. However, this increase in cost can be balanced out because small and half portions can attract more consumers and hence increase the total sales volume. In addition, small portions and half portions have the following benefits:

1. Reduced waste: If a customer orders a large portion of a dish but can't finish it, then it will be wasted. Offering small portions and half portions can reduce waste and is also in line with the concept of environmental protection.

2. Meet personalized needs: some customers may not want to eat too much, or want to try more kinds of dishes. Offering small portions and half portions can meet these individual needs, and also enhance consumer satisfaction.

3. Lowering the price threshold: Some consumers may feel that the price of large portions is too high for them to choose. Offering small portions and half portions can lower the price threshold and attract more consumers.

So although promoting small portions and half portions will increase some costs, their benefits can lead to more revenue and satisfaction, which in turn can be beneficial to the development of the business.