Purchasers and bidders, in the sense of Public procurement law, represent one of the most important factors of the economic and social system as a whole. Their significance is multiple, and due to a difficult situation and the period of posteconomic crisis, the idea of necessity of a change in business operations of the participants in business environment is emphasized, especially in the public sector, in order to reduce to a minimum or completely eliminate the multiyear losses in business operations, which represent a crucial, but not the only, indicator of business success. Radical turn in the sense of business operations of the purchasers represents a risk. The more radical the strategic option, the greater the risk. However, this paper rests on the idea that the turn is not the strategy which should be applied to the purchasers and the large business systems in public sector, because by radical changes in one segment of the large system we can disturb its other parts and experience fatal consequences for the system as a whole. Instead, a situational, adaptive model is suggested, with the dominant application of incremental, „stepby- step“strategic steps, in order not to disturb the structure of the system. Also, besides the measures connected to the current business operations, in certain segments we mention the factors which are not absolutely in reach of large business systems, but they would significantly contribute to better business operations and of course to rehabilitation of losses. Everything mentioned, regardless of the level and correlations between the mentioned factors, is shown through the thematic of public procurements, through which the contracting of the largest number of businesses in public sector happens.