Although MCM10 clearly improves the ability of the CMG to bypass a lagging strand block, their conclusion that this is due to CMG/DNA isomerization may be premature. A simpler explanation is that the MCM10-dependent improvement in helicase activity provides the force needed to drive the CMG through the block. Notably, this is consistent with their previous finding that the CMG alone (in the absence of MCM10) can dislodge a block potentially mediated by a single streptavidin from either strand. Why, then, should not a motor with dramatically improved activity (30-fold!) be able to bypass two such potential road-blocks? Additionally, these conclusions are based on the premise that the CMG does, in fact, encircle two strands. However, the background biochemical work on which this manuscript is based (Langston and ODonnell 2017 eLife) came to this conclusion by comparing the CMG's ability to bypass tandem biotin-streptavidin blocks on leading and lagging strand templates, where they find both able to block progression. This result by itself would be consistent with this conclusion but provides no direct evidence for the model. Other models include an outside path for one strand that must interact with the outer surface. Further and perhaps more important beyond model building, for this work and previous studies from the group, they fail to mention in their paper that the two bulky adducts on the lagging strand are placed at half the distance as those on the leading strand. Although their recent EM structure suggests that DNA forks engage further within the protein than initially anticipated, the lagging strand is still, nonetheless, excluded, and double-stranded DNA never enters the central channel -how deep one must go to be in the "central channel" is, of course, perhaps semantics.