The 35-day minimum applies to public sector procurement under EU/UK directives, not the private sector. In private procurement, response times should be proportional to the complexity and value of the requirement. Simple RFQs may require only a few days, while complex tenders involving technical submissions may justifiably need weeks. Responsible sourcing involves ensuring suppliers have fair opportunity to respond adequately, but without unnecessary delays that could affect business needs. Therefore, rigidly applying a fixed number of days in the private sector is neither necessary nor efficient.