Sprint Contract Overrun: Updated Causal Taxonomy from 80+ Cross-Venture Sprints
Abstract
TPL-2026-005 established that sprint-contract discipline reduces overrun rates in solo-operator agent-mediated work (median overrun 78% → 12%). That paper measured the effect; it did not decompose the causes. This paper extends that work with a causal taxonomy derived from 83 sprint contracts across three TruPath ventures (Quantum Caddy, Mile High Golf, Parley / cross-portfolio). We identify six root-cause classes that account for 94% of all overrun: scope-creep-in-flight, definition-of-done ambiguity, dependency-surface underestimation, agent-iteration overhead, hardware-external blocking, and operator-attention fragmentation. Frequency and severity differ significantly by venture: QC sprints are dominated by agent-iteration overhead and hardware blocking; MHG sprints by dependency underestimation and external blocking; Parley by definition-of-done ambiguity. An intervention table maps each cause class to the technique that most reduced incidence. All figures are illustrative; see §6.
1. Background
TPL-2026-002 [1] established the sprint-contract effect: adopting a structured sprint-contract discipline (pre-work definition of done, enumerated failure modes, gate-out acceptance criteria) reduced median overrun from 78% to 12% across 48 contracts shipped over 16 weeks. The reduction was directionally consistent across all three ventures and all work types. But the paper was an effect study, not a cause study. It established that the discipline worked; it did not explain why sprints overran in the first place.
That gap matters for two reasons. First, knowing the causes allows targeted intervention: not every overrun is caused by the same thing, and a blanket sprint-contract discipline that addresses scope-creep will not reduce overruns caused by hardware blocking or agent-iteration overhead. Second, the venture-specific cause distribution differs enough that a cross-venture portfolio cannot be managed with a single overrun-reduction strategy.
Estimation research in software engineering has long cataloged the structural causes of schedule overrun [3] [4]: unknown unknowns, optimism bias, planning fallacy, integration tax, and the specific pathologies of multi-person team coordination. Solo-operator agent-mediated workflows reproduce some of these causes faithfully and introduce new ones that are specific to the LLM-agent context: agent-iteration overhead (the model requires more back-and-forth than estimated), hardware-assumption failures that block unrelated work, and context-window pressure that causes the agent to miss scope constraints stated earlier in a session. This paper develops and validates a taxonomy of these causes from the TruPath portfolio.
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Sprint Contract Overrun: Updated Causal Taxonomy from 80+ Cross-Venture Sprints
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