Follow-on duration limit for GSA Schedule Task Orders FAR Subpart 8.4

The exception states “in the interests of economy and efficiency...”  so it boils down to discretion and deciding are you wasting government’s  and industry’s time with competing knowing which source will likely win?  No, there’s no absolute time limit and you have to use judgement.  It all depends on the exact nature of the requirement and what the incumbent possesses in terms of techniques, skills, methodologies , expertise, and approaches.