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tokens: may be that star formation is more burst-like (e.g., higher specific SFR; Schreiber et al. 2015 ) at higher z . Intense short-duration starburst episodes may be capable of clearing sightlines through the local ISM, resulting in increased ionizing escape during periods of lower activity, giving rise to the trend in Figure 8 . 5. SUMMARY We present intermediate-resolution absorption-line spectroscopy for four new gravitationally lensed sources, which, together with our earlier work (Jones et al. 2013 ), provides a total sample of seven star-forming galaxies in the redshift interval 4 z 5. Our S/N in all cases is adequate to sample the depth of absorption in low-ionization species, which can act as a valuable indicator of the covering fraction of neutral hydrogen. We describe two methods to convert this covering fraction into estimates of the fraction of LyC photons that are capable of reaching the IGM and undertake a critical analysis of possible uncertainties in our results. Our enlarged sample strengthens the trends discovered in our earlier work. In particular, we find the following: 1. The amount of absorbing gas varies significantly from galaxy to galaxy across our sample. However, only two systems are consistent with a complete coverage of low-ionization gas. The median observed covering fraction is 66%. Following a correction for reddening based on a dust-in-cloud model, we infer a median absolute escape fraction of LyC photons of 19% ± 6%. 2. We discuss various uncertainties in this estimate, including the possibility that the stellar radiation has different covering fractions depending on its ionizing capability, as well as scattered photons that could fill in the absorption-line profiles, mimicking a reduced covering fraction. We demonstrate that, even in the extreme case, these issues would only lower the escape fraction to no less than 11%, a value in broad agreement with independent estimates based on recombination studies of the IGM probed by QSO absorption lines. Further study of low-ion absorption lines in nearby galaxies with recent LyC detections will help determine the degree to which covering fractions may overestimate f esc . 3. For one of our lensed sources, MS 1358, we demonstrate that the low-ionization gas is clearly spatially inhomogeneous, with covering fractions ranging from 40% to 100% across various star-forming clumps. Although our sample generally strengthens the correlation we found earlier whereby the escape fraction increases with the equivalent width of Ly α emission, the scatter increases when we consider trends in the individual star-forming clumps in MS 1358, consistent with recent numerical simulations. As the escape fraction is anticorrelated with the local SFR, this suggests a time delay between a burst and the emergence of leaking LyC photons. 4. Overall, our observations indicate significant variations in the escape fraction, both from galaxy to galaxy and spatially within an individual galaxy.