Subaperture stitching extends measurements such as interferometry by combining several overlapping measurements into a single, high-accuracy estimate of the overall image. In designing a subaperture measurement regimen, there are several tradeoffs related to size, quantity and locations of subapertures within the full aperture of the test optic. Understanding how individual subaperture measurement noise couples through these parameters into errors in the final stitched map is important for estimating overall system performance. In this work, we explore parametric rules for estimating the accuracy of stitched results based on subaperture geometry parameters and noise characteristics for a self-calibrating system where both a test optic and reference optic are simultaneously determined. From these rules, we examine types of errors introduced by stitching which enables confidence estimates for the final stitched map surface quality.